Long Range Shooting & Hunting
By: Daniel Lilja
This section is based on a series of articles that appeared in PRECISION SHOOTING magazine in the late 1980’s and early 1990’s. They were later combined into a chapter for a book published by PRECISION SHOOTING.
When we first published this article section on our web site I didn’t include this article on long-range shooting. Long-range hunting has been a controversial subject in some circles. And I didn’t want to be responsible for contributing to what some might consider as an unfair or unethical sport. But after thinking about this for a year or so, I decided to include this article. There is a caveat in addition to this introduction at the end of the article too. So read the following for what it is: my attempt to explain methods and detail equipment that other shooters and I have used to successfully shoot at extended ranges, in a somewhat scientific way. This latest revision was edited in July of 1998 and a few new pictures were added at that time. Note: a few additional pictures have been added since the 1998 revision including the 1100 yard antelope picture.
The small band of antelope looked a long way off when we spotted them from the ranch road. They were, as the rangefinder later proved, right at 1100 yards. They were far enough away and it was early enough in the hunting season that the antelope were not alarmed by our pickup truck as it rolled to a stop and Bill and I put our binoculars on them.
We were hunting antelope in northeastern Montana during the first week of the 1988 season. There was one small buck in the band and I decided I would try for him with my last tag. We were allowed up to three antelope each in the area we were hunting but only one could be a buck. Quickly I pulled my portable bench from the back of the pickup and set it down. As I got out the rangefinder and determined the distance to the antelope buck, my hunting partner, Bill, was getting the sandbags set up on the bench and getting out my rifle. I looked up the distance on my computer generated drop chart and cranked the appropriate scope adjustment into the 24x Leupold target scope.
About five minutes after deciding to shoot the antelope buck I was setup and had him centered in the scope. Bill had also set up our spotting scope and was waiting for me to tell him I was ready to shoot. I placed the quarter minute dot just behind the shoulder and centered vertically. “Ready” I told Bill and squeezed the trigger. “You hit him!” Bill yelled. Indeed I had, as I pushed the rifle forward from recoil I could see through the scope that I had hit the buck in the center of the body and that he was down and about dead. The 30 caliber 220 grain Sierra boattail had hit him in the center of the body and within a couple of minutes he was dead. He never got up after first being hit.
Luck you might say. Well luck has a lot to do with most game shots whether they be long ones or close in the black timber. In the following article we will take an in-depth look at the type of equipment and knowledge it takes to consistently hit targets from 500 yards on out to over a mile away.
We will take a look at the rifles used in this type of shooting and the various cartridges used by serious long-range riflemen. Also, we’ll learn how to make a drop chart based on the cartridge and load we are using and also take into consideration atmospheric conditions that can affect bullet trajectory.
The drop chart is a key element in the shooter’s poke. With it he knows how many clicks to dial into his scope for a dead center hit. Another very important area is the optics used by the long-range shooter. These include rifle scopes, optical rangefinders, and other support optics such as binoculars and spotting scopes. Lastly we will look at what can go wrong in long-range shooting. We’ll find that there are some common problems and pitfalls that can cause misses and poor grouping at long-ranges.
To start with we must have a solid shooting platform. The portable bench I mentioned at the beginning is one made by Armor Metal Products of Helena, Montana. As their advertising states these benches really are “rock solid”. I have the four leg model and have been very satisfied with it. The designer of the bench, Lee Andrews, is a veteran long range shooter himself and designed the bench for his own needs. The bench is a very high quality portable and leaves nothing to be desired. Along with a solid bench the shooter will need a stool to sit on.
The sturdiest bench available is of little use if the rifle is not also properly supported on a set of sand bags designed for the job. I use a Wichita front pedestal with a flat bag on top and a rabbit ear type rear bag. The Wichita is easily adjustable for elevation changes but there are others that will work as well.
(Since I originally wrote this article I’ve made a modified shooting bench that can be seen in the photograph below. It allows more vertical adjustment than a conventional pedestal. And the radiused contour of the bench enables shots of to the either side to be made easily.)
In short, the long-range shooter requires a solid bench and sandbag setup. One that does not move or tip when he is about to shoot. A lot of game has been shot over the hood of a pickup or jeep but when it comes to serious long-range shooting we must do better.
I mentioned at the beginning the use of a rangefinder. This piece of equipment is invaluable to long-range shooting. It is also the hardest piece of equipment to obtain that we will mention. We will discuss these rangefinders in more detail later in the optics section.
(Since this was first written in 1988 there are a number of excellent laser range finders on the market. The optical range finders still work very well but haven’t been made since the early 1960’s. They are also slower to use and much heavier and bulkier.)
Combined with the use of the rangefinder, a drop chart detailing the bullet trajectory is essential. Many shooters today have either a personal computer or have a friend that does. With an exterior ballistics program a very accurate drop chart can be generated quite easily. There are many good ballistics programs on the market but our personal preference is for the simple to use Tioga Engineering program.
What is needed is a table that indicates the bullets path every 25 yards or less, on out as far as we care to shoot. The program usually is run so the calculations are based on a 100 yard zero and from this the number of minutes of scope adjustment can be determined for any given range. In my opinion dialing the adjustment for minute of angle change into the scope is the only method to use for long-range shooting. Holding over the correct amount is impossible. The midrange height of the bullet for the shot I described at the beginning of this article was over 20 feet.
Referring to my drop chart, to hit the antelope at 1100 yards, I needed to put into the vertical adjustment on my scope 25 1/4 minutes of adjustment, which at 1100 yards is 277 3/4 inches. Had my range determination been off 25 yards one way or another the bullet would have been high or low 14 inches or so. Without any doubt the scope used must be very reliable and have accurate adjustments.
Two developments available to shooters in the last 10-20 years have been a real boon to long-range shooting. They are the proliferation of high quality and relatively inexpensive chronographs and as mentioned above, ballistics programs designed for use in personal computers.
Cartridges and Bullets
One of the keys to successful long-range shooting is in shooting a quality bullet of high ballistic coefficient at high velocity. As the weight of a bullet goes up for any given caliber and if the shape stays the same, the ballistic coefficient goes up, as does the sectional density. Another way of increasing the ballistic coefficient is through stream-lining of the bullet’s shape. This is the reason for boattails and long pointed hollow points.
For extended range shooting we are interested only in bullets of the highest ballistic coefficient. For example the 30 caliber 220 grain Sierra has a ballistic coefficient of .655. Compared to the 150 grain Sierra spitzer with a ballistic coefficient of .409 the heavier bullet is the clear choice for long range work. Using the figures in the Sierra manual, firing these bullets out of a 300 Winchester magnum the top load listed will give us a velocity of 3300 fps with the 150 grain spitzer. The top load with the 220 grain Match King yields 2700 fps. At 1000 yards however the 150 are travelling along at 1254 fps and have 524 ft-lbs. of energy. The 220 however is moving at 1491 fps and has 1086 ft-lbs. of energy. Bullets of higher ballistic coefficient are also as a result less affected by changes in the wind.
Bullets should be selected on the following grounds. They must be accurate at long-range and of high ballistic coefficient. Therefore in making the decision to select a match type bullet over a soft point spitzer or the other way around, I would select the bullet that proved to be the most accurate in my rifle. You must hit them first.
Most of the animals I have seen killed at long-range have died very quickly. I have also seen evidence that some of the match bullets have opened up way out there. My friend and experienced long-range hunter Darryl Cassel and I have discussed this and he reports excellent killing characteristics from the 200 grain Sierra Match King fired from a 30-378 Weatherby. I remember looking at a picture of a big black bear he shot, at about 700 yards with that combination, that showed a tremendous wound cavity. Darryl said he dropped like a sack of potatoes too. I recall a mule deer buck I shot with the 270 Weatherby and 130 grain Ballistic Tip at a muzzle velocity of over 3500 fps. That buck died as quickly as any game animal I’ve seen hit at any range – immediately.
I’ve talked to quite a few hunters that have used the 300 grain Sierra .338 bullet at long-range on game like elk, deer and bears. They are reporting very good killing qualities from this bullet. The down-range energy level is tremendous.
The hot 22 caliber cartridges shooting the 69 grain Sierra or 68 grain Hornady make excellent long range varmint cartridges. Jimmy Knox of JLK Bullets makes an 80 grain very low drag boattail bullet. Sierra also has come out with a similar bullet also of 80 grains. In the 224 Clark these bullets can be pushed over 3500 fps. They are extremely accurate and make for an excellent long-range varmint bullet. Their use though should be limited to varmints.
The 105 grain custom Berger bullet makes an excellent long-range bullet when fired at high velocity in a big case. Sierra also now offers a 107 grain VLD type bullet, another excellent choice for long-range varminting. The 6mm’s are on the light side for big game hunting but are suitable for antelope hunting and excellent for varminting. The key here again is shooting a high ballistic coefficient bullet at high velocity.
Some of my earliest long-range shooting came with the 25-06. I used it to shoot mule deer, antelope, and a couple of black bears from 400-500 yards or so. I used 100-120 grain bullets and they all seemed to work well for me. The 100’s shot flatter but the 120’s penetrated better. I also shot a bunch of prairie dogs and the occasional coyote with it using lighter weight bullets.
That 25-06 is now a 257 Weatherby and that cartridge is more of the same but better. I usually shoot the heavier bullets in it.
Firing 140 grain bullets in a magnum .264 is more of the same. The 6.5-300 Weatherby magnum used to be a popular long-range cartridge. It is still a very good cartridge with the right bullets but it has been somewhat over shadowed by some newer developments. Sierra makes some excellent heavier weight Match Kings for this caliber.
The .270 Weatherby is another good long-range cartridge and is one of my personal favorites. I use the 130 grain bullets in my 270 for the simple reason I can get over 3500 fps from my 30″ barrel. For shots out to 600 yards or so the 130 shoots flatter than a 150 grain bullet and I use it for my moderately long-range shooting. I’m on my second barrel now in the 270 Weatherby and it continues to be a star performer especially with both the 130 and 150 grain Nosler Ballistic tips. It is not at all unusual to get sub half inch 5 shot groups at 100 yards with the 130 Ballistic Tip and with the velocity over 3500 fps. Besides being an excellent deer and antelope cartridge, I have also used this rifle for shooting rock chucks on out to 800 yards or so.
In Superior, Montana the local gun club once held several dynamite shoots every year. We shot at a half stick of dynamite placed in an orange painted pop can. The close cans were about 500 yards and the farthest one close to 1100 yards. The above mentioned 270 Weatherby has accounted for many dozens of these cans over the years.
When we step up to the 7mm’s the heavier bullets in that caliber start to have enough weight that their down-range energy levels are high enough to be used for long-range big game hunting of larger animals. In the 7mm’s all the magnums will work well with the 7mm-300 Weatherby, and it’s more recent counterpart, the 7mm STW (which is the 8mm Remington magnum case necked down) giving the highest velocity.
I have also experimented with a 378 Weatherby case necked to 7mm and shortened to 2.540″ with a 30 degree shoulder. With it, in a 30 inch barrel, I can get up to 3500 fps with a 168 grain Sierra. A true case of overbore but velocity is the name of the game in long range shooting. I later rechambered this barrel to a full length 7-378 Weatherby thinking I could get even more velocity. To say that this cartridge was a disappointment is an understatement. I was able to burn more powder all right in the bigger case, but I couldn’t get anymore velocity. In fact with some bullet weights I even lost velocity. I had gone past the point of no return.
The big 30’s are the most common long-range cartridges used. Again all of the magnums work well, as do many wildcats. The 30-8mm Remington Mag or an improved version of it and the 300 Weatherby are near the top in my opinion. The 300 Weatherby is another of my personal favorites. In the 1992 hunting season, I used it to shoot a sheep at 760 yards, one shot through the head, and a whitetail deer at 890 yards. The load was a 220 grain Sierra Match King at 2900 fps.
On another hunt I shot a mule deer at just over 1400 yards with an improved 300 Weatherby and 220 grain Sierra Match Kings. The muzzle velocity from this combination was just under 2900 fps out of a 30″ long barrel.
Another popular wildcat is the 378 Weatherby case necked down to 30. There are several versions, from full length down to 30-06 length. Depending on the barrel length and powders used, the full length version is capable of driving the 220 grain Sierra up to 3300-3400 fps.
Another excellent 30 caliber cartridge is based on the 416 Rigby case. I have one that has been improved slightly and has a 35 degree shoulder. It basically is the same as the 30-378 Weatherby. Its advantage however, from my view point, is that it has no belt. This fact eliminates some of the sticky case problems associated with the 378 Weatherby based wildcats. Because there is no belt to expand, as on the 378 case, I can boost pressures a bit over the 30-378. In my opinion this just might be the best 30 caliber long-range cartridge.
Another caliber worth looking at is the .338. Starting with the 338 Winchester magnum and working up to the 340 Weatherby and several wildcats of similar case capacity or the big .378 Weatherby case or 416 Rigby necked down, all are potent numbers. There are 250 grain bullets available from Sierra and Nosler that really pack a lot of punch down range. I remember watching a friend shoot a big 6 point bull elk with his 338-378 at about 600 yards. He dropped instantly when the 250 grain Sierra hit him. This Sierra has a ballistic coefficient of .598, which is quite high. We now have the excellent 300 grain Sierra Match Kings for this caliber too. The ballistic coefficient of this bullet is close to .800, the highest of any bullet available for any caliber not including the big 50’s. This big Sierra is a true match quality bullet capable of outstanding accuracy at long-range. And from my experience and that of other long-range hunting friends, it works well on game too.
There is a group of shooters that fire the 50 caliber Browning machine gun cartridge from rifles for extreme long-range shooting. The 50’s are truly big, slinging 650-800 grain bullets at roughly 30-06 velocities, no other small arm can compare with them. Some would argue that the 50 is not a small arm but technically speaking they are classified that way.
I shot a 50 BMG with some friends at a shot out tank hull at 2000 meters. With it we could easily spot our hits. With some of the smaller cartridges we have mentioned, shooting something at that range would be out of the question.
Historically the 50 caliber (actually .510″) has suffered from a lack of match quality bullets. In the last several years experimenters have been playing with various lathe turned solids. They have used materials such as brass, bronze and even steel for these bullets. Their results have been worthwhile, as accuracy has reached new levels in the fifty. Hornady has made a match type bullet for this caliber called the A-Max. This Hornady offering and the custom lead core bullets made by Lynn McMurdo of Wyoming are the best hunting bullets for the big fifty.
A few years ago a friend told me about shooting a cow elk at about a mile with his fifty and the McMurdo bullet. He got zeroed in on the elk and hit her in the lungs. She died instantly.
I’ve used my fifty to shoot rock chucks out to a mile or so. Truly a lot of fun when you can hit a target that small at distances like that.
Large case capacities and heavy bullets require the use of the slowest burning powders for maximum velocities. Starting with 4831 on the fast side, some powders that have worked well are H870, WC872, Reloader 22, H1000, H570, H5010, T5020, IMR7828 and various lots of 5010 distributed by several other sources. Not being a canister grade powder, 5010 varies quite a bit in burning rate. When working with a new lot of 5010 start low on the charge weight.
Another good powder source is the slow burning offerings from VihtaVuori. These are clean burning and consistent extruded powders.
I have probably used more 5010 than the others and have found it to be clean burning and predictable as one approaches maximum loads. I have also used H1000 quite a bit and like it very well. In the 300 Weatherby with heavy bullets it has given me excellent accuracy and top velocities.
I have used the Federal 215 magnum primer almost exclusively and have found it to be a very good primer for this application. It was developed for use in the 378 and 460 Weatherby magnums and it does its job well. In the 50’s the CCI and RWS primers are good choices with the CCI being a little hotter.
For a serious long-range rifle I would recommend a tight neck chamber and turning the case necks for maximum loaded round concentricity. I even have a tight neck in my big 50 BMG.
My 270 Weatherby does not have a tight neck, in fact it even has the long Weatherby freebore and it still shoots very well. The point being that turning necks is not absolutely necessary but a good idea.
What kind of rifle does it take to handle these cases and hit targets out to over a mile away? The answer for the most part is a big heavy benchrest type rifle; usually a single shot version with a high quality, high magnification target scope on top.
Single shot actions offer stiffness over a repeater and the lack of a quick second shot is no handicap for this type of shooting. What is needed is a benchrest type action built to handle magnum type cartridges and the stiffness to support a long, heavy barrel. Hall Manufacturing of Clanton, Alabama offers its Express action for this type of shooting and it is a good one. Allan Hall recently introduced another action for the big 378 and 416 Rigby type cartridges. This action is designated as the `G’ for giant and is basically a bigger version of the proven Express.
A friend of mine, Gerry Geske of Superior, Montana has recently designed and built some big actions for these big cases. His action features a three lug bolt and two cocking pieces that make for a very smooth operating bolt.
Another recent entry into the big cartridge – big action game is the very nice BAT action made by Bruce Thom of Rathdrum, Idaho.
There are just a few actions that will work with the large diameter 378 and 416 Rigby cases with the big custom types being the best.
Most of the commercial actions that come with a standard magnum type bolt will work for the standard magnums such as the 300 Winchester and 300 Weatherby. Almost all of these actions however are repeaters and as a result not as stiff as the big single shot actions. Remington 700 actions can be fitted with a large aluminum sleeve, which increases stiffness as well as increasing bedding area, both of which help accuracy. Alvin Davidson makes a good one. An alternative to sleeving a Remington 700 is to use the barrel block bedding method. With the barrel block the action floats so no bedding problems associated with smaller repeater actions crop up.
Without a doubt one of the most critical components of the rifle is the barrel. Suffice it to say that only a barrel from one of the makers of high quality benchrest barrels is up to the task of precise long-range shooting shot after shot. Barrel length is an important consideration when looking for top velocities, especially when burning the slow powders. A minimum length should probably be about 26 inches. I prefer about 30 – 36 inches but some shooters like even more. I know some shooters that are using barrels as long as 40 inches and getting very high velocities. With barrels over 32″, or so, a barrel block becomes something to think about when building a new rifle. There are always trade-offs, longer length means increased velocities but also increased powder and jacket fouling and more barrel whip.
Large diameter barrels are stiff and that is what we are looking for. The barrel on the rifle I used to shoot the antelope mentioned at the beginning is 30 inches long and 1 1/2 inches in diameter its full length. The entire rifle weighs 33 pounds with the barreled action weighing 20 pounds alone.
The long-range shooter is usually shooting the heavier bullets for a given caliber and often these are boattail bullets too. This means that faster twists are required to stabilize the long bullets. In the 22 and 243 caliber the current VLD type bullets are best with an 8″ twist.
In 25 caliber all of the bullets available that I am familiar with will work well in a 10″ twist. We may see some newer developments in this caliber that will require a faster twist though.
In the 264 caliber everything now on the market will work in an 8″ twist and most bullets including the 140 grain boattails will work in a 9″ twist although the 8″ is required for the 155 grain Sierra Match King.
Until Nosler came out with their Ballistic Tip bullets in 270 caliber, there was not much available in match quality bullets. The 150 grain bullets will work very well in a 10″ twist. And Sierra now offers a 140 grain Match King in .270 caliber.
The 168 grain Sierra Match King in 7mm is stabilized quite well in a 9″ twist and any bullets that are lighter in this caliber will also work in a 9″ or a 10″ pitch.
With both the 308 and 338 caliber the 10″ twist will be appropriate for any of the heavier bullets including the 240 grain 30 caliber and the 300 grain 338, both are Sierra Match Kings.
In 50 caliber the 15″ twist has been standard and it will handle most of the bullets out there.
As we mentioned earlier, the scope is an extremely important part of the long-range rifle and we will take a close look at it later.
In stocks, a wide flat fore end for minimum tipping on the sand bags is preferred. Either wood or fiberglass stocks are entirely suitable although most new rifles being built today are fitted with a fiberglass stock. Lee Six of Six Enterprises makes two good unlimited style benchrest stocks in fiberglass.
Another excellent long-range type fiberglass stock is the Tooley version made by McMillan. This stock was developed by gunsmith Dave Tooley of North Carolina. McMillan stocks also make several excellent stocks for the 50’s.
Developing a Drop Chart
It is very important to know the muzzle velocity of the cartridge-bullet-rifle combination. Knowing the velocity is a key in developing an accurate bullet drop chart. It is essential to chronograph the particular load to be used. The same load fired in another rifle or barrel might not yield the same velocity. Also, most of the big game seasons, at least in my part of the world, are in the colder fall months. The actual chronographed muzzle velocity on a cold, 35-degree November day might be much different than the velocity of that same load fired on a hot July afternoon. It is not uncommon to have a 100 fps difference in velocities due to temperature changes. That amount is easily enough to cause a miss at long-range.
Determine Ballistic Coefficient
After the muzzle velocity is known, the appropriate ballistic coefficient for the bullet should be determined. All bullet manufacturers publish ballistic coefficients for their line of bullets. That value may or may not be the correct one to use however, for precise long-range work. Like prices on the window sticker of a new car, the numbers don’t always say what they mean.
Sierra is the only manufacturer to use the multiple ballistic coefficient approach. They have determined through firing tests that the ballistic coefficients for their bullets change as the bullets go through different velocity zones. Actually, all bullets that have their coefficient based on the G1 drag function, and that have a shape different than the original model, have a ballistic coefficient that varies with velocity. This covers virtually all small arms bullets with a C1 ballistic coefficient. Generally speaking, the ballistic coefficient decreases in value as velocity decreases.
The use of computer trajectory programs, along with the use of chronographs, has been a tremendous aid in calculating bullet drop charts for long-range shooting. There are a number of programs available. I have experience with some of them. Probably any of these programs which include a bullet path computation could be used for this work.
If Sierra’s trajectory program is used to compute bullet drop, it incorporates the multiple ballistic coefficient feature. Sierra’s reloading manual lists the coefficients for each bullet through the velocity ranges. Two other programs that I have used with good success are one by ProWare and one by Tioga Engineering.
Of the Sierra bullets that I’ve used, the multiple ballistic coefficients seem to be accurate. This is based on actual observed bullet drop at long-range. The one exception to this is the 250 grain 30 caliber bullet. Sierra lists the coefficients for this bullet as .697 for velocities above 2600 fps, as .748 for 2250-2599 fps, as .777 for 1751-2249 fps, and as .743 for 1750 fps and less. My experience indicates that the ballistic coefficient is closer to the .697 value for all velocities. This was true at least in the barrel I fired them, shooting the bullets over two chronographs to determine ballistic coefficient. Actual drop figures also seem to indicate a coefficient of about .700. Sierra has replaced this bullet with a 240 grain version and its coefficient will be just a bit lower.
If the program being used to calculate drop does not have a multiple ballistic coefficient feature and Sierra bullets are being used, I’ll pass on a tip I learned from Bill Davis of Tioga Engineering. He suggested that the correct coefficient to be used could be found by using the remaining velocity figures from Sierra’s published trajectory data and running them through a computer program that calculates ballistic coefficient from two ranges and velocities. Sierra lists velocities on out to 1000 yards.
For example, if the bullet being used is the 220 grain 30 caliber version at a muzzle velocity of 3000 fps, the remaining velocity at 1000 yards is 1706 fps. This 1000 yard velocity is the same as if a .641 ballistic coefficient were being used in lieu of multiple ballistic coefficients. Sierra lists the coefficients of this bullet as .655 for 2400 fps and above. It is .630 between 1601 fps and 2399 fps, and for velocities less than 1600 fps it is .610. I have also used a dual chronograph setup and fired this bullet over it. I found the ballistic coefficient to be .640 at a muzzle velocity of 3100 fps. I have used this value, .640, in preparing drop charts for this bullet and found it to be just about right.
The ballistic coefficients for two other Sierra Match Kings used for long-range work, the 200 grain 30 caliber and the 168 grain 7 millimeter were also figured in this manner. They are .597 for the 30 caliber at a muzzle velocity of 3200 fps and .625 for the 7 millimeter bullet at 3200 fps. I have not shot either of these bullets enough to know how these figures bear out in actual shooting though.
The ballistic coefficients for Nosler’s Ballistic Tip line of bullets seem to be quite useable for long-range work. As I mentioned earlier, I have not shot these bullets at long range as much as the Sierras. When I have, and used their ballistic coefficients, the drop figures seemed accurate.
Walt Berger’s 210 grain .30 caliber VLD seems to have a ballistic coefficient about the same as the 220 grain Sierra Match King. This Berger bullet is another excellent long-range performer.
Now that the correct sea level ballistic coefficient is known, the atmospheric conditions for the shooting trip must be taken into consideration. In general terms, as altitude increases or local barometric pressure decreases, the density of the air decreases. Also, when air temperature increases, air density decreases. When the air is thinner than the standard sea level atmosphere, bullets will perform better. The bullet will drop less over a given range and the wind will blow it off course less. The amount of increased bullet performance can be simulated by assuming that it has a ballistic coefficient higher than its sea level value. It is the sea level ballistic coefficient that is listed by the bullet manufacturers.
A change in humidity also has an effect on air density, but it is very minor and can be ignored. Normally, it will change a ballistic coefficient by less than one percent. Contrary to popular belief, higher humidity actually decreases air density. Although it seems thicker to us mortals, for bullets and airplanes it is really slightly thinner.
Altitude has the biggest effect on air density, followed by changes in air temperature. When shooting in mountainous country, altitude changes should be taken into consideration. Temperature will usually decrease however, when altitude increases, each somewhat offsetting the other.
It should be noted that there are two basic methods that can be used to arrive at the correct ballistic coefficient for non-standard atmospheric conditions. Most trajectory computer programs have the capability of handling changes in altitude, and usually temperature changes as well. I know of just one that will also account for barometric pressure changes.
Fluctuations in the barometer can be easily simulated. An inch of change in barometric pressure is equivalent to an altitude change of 1000 feet. If the effects of lower barometric pressure is questioned, the altitude should be increased the appropriate amount. A higher pressure is simulated by decreasing altitude. For example if the barometer reads 30.35″, the local pressure is .43″ above standard, with 29.92″ being standard (30.35 – 29.92 = .43). If the shooting site elevation is 3400 feet, the above standard pressure can be simulated by entering into the program or calculations an elevation of 2970 feet [ 3400 – (.43 x 1000)=2970 ]. With this approach, the program handles the math in the air density calculations. Letting the computer do the air density computations is the easy way. A disadvantage however is that not all of the programs allow both altitude and temperature inputs. And as I mentioned, only one considers barometric pressure.
The other method deals directly with the sea level coefficient before the computer program is used. If this route is chosen, the altitude input in the trajectory program should be zero for sea level and the temperature should be 59 degrees, standard for sea level.
For example if we have decided to use the 220 grain, thirty caliber Sierra bullet and a ballistic coefficient of .640, what would the equivalent ballistic coefficient be for an elevation of 4500 feet and a temperature of 50 degrees? Using the formulas for these variables, it would be .737. The bullet would perform as if this were its coefficient instead of .640. When entering the variables into the program, the correct coefficient to use would then be .737 and altitude zero. Temperature, if it is a variable, would be 59 degrees.
Shooting uphill or downhill will result in high shots if the angle is roughly 15 degrees or more or if the range is very long for lesser angles. The actual bullet drop is dependant on the true horizontal distance to the target not the slant range. Our range finders measure the slant range. Again there are several methods to determine the amount of correction necessary. Most, if not all, ballistic programs can take into account angled shooting and print out the correct drop for any range. The Sierra handloading manual in the exterior ballistics section deals with this subject with an example.
The Sierra manual has a table of factors that in use are multiplied by the total drop in inches, for the slant range to the target. The factors are .034 for 15 degrees, .134 for 30 degrees, and .293 for 45 degrees. There are more listed in the manual but these will give the reader an idea of the degree of change as the slope increases. Their use is simple. Let’s say that you were looking uphill at a mule deer buck that your range finder said was 675 yards away. Looking at your drop chart you read that for that distance you need 11 1/2 minutes of adjustment in your scope. The catch though is the buck is uphill at an angle of 30 degrees. Using these factors we take the total drop for 675 yards (which is 103.1 inches) and multiply by .134 (the factor for 30 degrees) and the result is 13.8. That is to say that the bullet would impact about 14 inches high if we did not allow for the angle. Fourteen inches is about two minutes of angle at that distance. From this example we can see that it would be easy to miss that buck had we not taken into account the steep angle to the deer.
Generating Drop Chart
Now that we know the appropriate ballistic coefficient and the muzzle velocity for the bullet, it is a simple matter to run a drop chart from the computer program. Almost all the shooters I know base their charts on a 100 yard zero for the bullet. It is from this known zero that all scope corrections are made for longer shots. Target scope knobs are calibrated like a micrometer, so once the setting for zero is known, it is easy to return home. The drop chart might be as simple as the number of scope `clicks’ required for each range or it might be a computer-generated minute of angle (or `MOA’) correction for each range. Whatever is used, it must be a simple and fast system for putting the correct amount of adjustment into the scope knob. Emphasis on simple.
It is important when developing the drop chart to have the yardage intervals close enough together that the amount of correction between them is not too great. For example in the sample chart, the interval for the longer ranges is 20 yards apart. This spacing means only about one minute of change between yardages on the table. If the interval was much greater, a little reading between the lines might be required for some distances. The easier it is to use in the field, the better. A piece of advice VCR makers should learn.
I am familiar with just one program that will calculate the MOA correction needed for each range. This is the program from Tioga Engineering.
It is fairly easy though, to calculate the MOA correction from just the yardage and bullet path or bullet impact figures. For example, if the bullet path was 210.7 inches low at 1000 yards, the MOA correction is found by first multiplying the range in yards by .01047. The second step is to divide the bullet path figure by this number. Plugging in the numbers it would be 210.7 / (1000 x .01047) = 20.12 or 20.1 minutes of angle. Using a target scope with quarter minute clicks, this would be 80 clicks. Using the figure of .01047 above yields the true MOA value with one minute of angle being 1.047 inches at 100 yards.
The true MOA value should be used if the scope adjustments are calibrated for actual MOA. Not all scopes are. Surprisingly not all scopes from the same manufacturer are based on the same value. Almost all target scopes are calibrated so that one click is worth, nominally, one quarter minute of adjustment.
Another problem associated with internally adjustable scopes has to do with the click value changing as the adjustment reaches the outer limits of its travel. One click in the center range of adjustments may not be worth the same as one click 35 minutes of adjustment away. The only sure method I know to check for this condition is to measure off 300 feet and set up a tape measure or yard stick and start clicking the scope.
If the scope adjustments are not based on true MOA but some other figure, such as 1.000″ at 100 yards, the actual MOA number can still be calculated. In the example above we multiplied the range in yards by .01047. If the clicks were based on 1.000″ at 100 yards instead of 1.047″, the range in yards should be multiplied by .01, not .01047. Other oddball click values can be similarly accounted for.
External adjustment scopes, such as the Unertl or Mitchell have an advantage over the internal variety in this regard. If the scope base blocks are spaced at 7.2″, the clicks of a Unertl will be worth one quarter minute of adjustment. With any other spacing the click value falls into the oddball category. Another advantage of the Unertl type scopes is the fact that the shooter is always looking through the optical center of the scope, regardless of how many minutes of adjustment are dialed into it. This is not true of the internal type. At the extremes of adjustment, there is some optical distortion in the internals, and as mentioned above the click value may change.
Despite the advantages of the Unertl scopes, almost all of my own shooting has been with the internally adjustable Leupold and Night Force target scopes. These have usually been in 24 power for long-range work or one of the variables from Night Force.
In this section we have found then, to hit a target, an accurate drop chart with scope adjustment figures for each range, based on the individual scope’s click value, is required. An accurate drop chart is generated by knowing the `correct’ ballistic coefficient of the bullet for the given shooting conditions, and knowing the actual muzzle velocity of the bullet.
This section will discuss the optical equipment used by the long-range shooter including more on scope choices. Perhaps more than any other type of shooting the long-range shooter relies on his optics, not only for shot placement but also for observing the target and determining its distance. There are then, three main categories of optics that the long-range shooter is interested in. The first includes binoculars and spotting scopes used in finding the target and spotting shots. The second category is the optical or laser rangefinders used in determining the exact distance to the target. The third is the rifle scope used on the big magnum rifles for precise shot placement.
Glassing for Mule Deer in the Missouri Breaks country of Montana.
Spotting Scopes and Binoculars
I have long been interested in binoculars and spotting scopes as well as most types of optical equipment. Over the years I have used quite a few different types and brands of scopes and binoculars. Until fairly recently, there were not many high-powered binoculars available, other than WWII-era Japanese battleship binoculars. Spotting scopes are wonderful for looking at or for something at long distances if you don’t plan on looking for any length of time. When I squint through a spotting scope for very long though, my other eye starts to give me trouble. Soon I find myself going back to a pair of binoculars to get away from the eye fatigue associated with the single spotting scope.
There are two different ways to use binoculars and spotting scopes when hunting. Some short range hunters only use their binoculars to look at game animals after they have already spotted them with their unaided eyes. The long-range hunter, on the other hand, often spots his game only after using his optics. Whether or not you are a long-range hunter, this technique is an excellent way to spot game and then sneak up on it. Much more game will be seen using this technique. In the areas where I hunt in the mountains, we usually glass open parks and older clearcuts and along the edges of the timber. In the open high plains country the game is easier to spot, but it’s surprising how much more game is seen looking through the right optics.
Several different high power binoculars are available today. Perhaps I should first define high power. I consider anything of 15 power or higher as being high powered. I have a pair of 10×50 binoculars that I use frequently, but when trying to judge antlers or tell which animal is the buck in poor light, they lack power if the distance is too great. I have found that a pair of 15×80 Steiner binoculars are excellent for general observation at long-range. Once an animal or varmint is spotted with these, I might go to something with more power but then again I might not. With the 10×50’s I almost always go to something with more power after the animal has been spotted.
A drawback to using too much power for general observation is the limited field of view with higher powers. When I’m scanning an opening, I like to cover as much area as possible without missing anything. Some of the clearcuts in which we find deer, and occasionally elk, are up to 200 acres or so–a big area to look at.
The amount of light that is transmitted to the eye through a scope is dependent on its power, the size of the objective lens, and the quality of the lenses and coating. The overall quality of the binoculars depends on these elements as well as the care in their assembly and the quality of the optical design. There are two types of quality pertaining to any manufactured product, the quality of its design and the quality put into its manufacture.
Coatings for lenses were developed during the WWII period, although most of the optics used in that war were uncoated. An uncoated lens loses about 5 percent of the light passing through it at each lens surface. Early coatings cut this loss to less than half that amount. The multiple coatings of today, however, reduce the light loss to less than one half of one percent at each surface. Each manufacturer seems to have a proprietary lens coating that is, in their opinion, the best available. No doubt there are differences in coatings. I think though, that there is very little practical difference in the coatings used by the manufacturers of quality products. The emphasis here is on quality optics.
The size of the exit pupil, which is the diameter of the little circle of light seen in an eyepiece held at arm’s length, determines how much light the eye receives. It is always expressed in millimeters and is found by dividing the size of the objective lens, in millimeters, by the instrument’s power. For example the 10×50 binoculars I mentioned have an exit pupil of 5mm since 50 divided by 10 is 5. The 15×80 binoculars would have an exit pupil of 5.33mm.
I’ve also used a big set of Russian binoculars, 20 power with 110mm objectives. The exit pupil on these is 5.5mm.
Under normal daylight conditions, the pupil of the eye contracts to a diameter of about 2mm. When this happens, an exit pupil greater than 2mm in a pair of binoculars is not necessary, some of that light is not used. When the light is poor however, as it is in the early morning and evening hours, the pupil of the eye will dilate to about 5mm. Under dark nighttime conditions the pupil may dilate up to 7mm. During the poor light hours, when game animals are moving, are when that large exit pupil will demonstrate its worth.
When looking for a pair of binoculars then, the greater the diameter of the exit pupil, the better its performance will be in poor light conditions. As was mentioned, generally speaking the eye will not dilate beyond 5mm, so a pair of 7×35 or 10×50 or 15×75 binoculars will offer about all of the light your eye needs and can use. This same principle applies to rifle scopes.
If higher-powered binoculars are desired there are two choices. The expensive approach is to try and find a pair of the already mentioned WWII Japanese naval binoculars. The Japanese models are preferred because they had developed the lens coatings earlier than the United States and employed them in these binoculars. As a result they are superior for poor light use. A common power and size for these was 20×120–truly a pair of big binoculars, with an objective lens diameter of about 4.75″.
Another approach is to assemble two spotting scopes together into a pair of binoculars. The 60mm Bushnell Spacemasters work very well for this and cost much less than original Japanese binoculars. The 22x wide angle eyepieces on the Spacemasters are a good way to go. They offer a wide field of view and a useable power with good definition. I have a single Spacemaster with this eyepiece and have used it when walking or riding my horse into an area, and weight is a consideration. That four legged beast comes in handy for packing out game too.
The 77mm Kowa spotting scopes also work very well for this application. I have used two of these in tandem and consider them to be as good or better than anything I have looked through. The large 77mm objectives mean a higher exit pupil value for a given power eyepiece. The set I used had the 25x long eye relief eye-pieces. I wear glasses, and this eyepiece allows me to keep my glasses on and still enjoy a full field of view.
The Kowa’s really showed their value on a recent elk hunt. We were glassing some natural openings near the Montana/Idaho divide one evening. About 15-20 minutes before it was completely dark, we spotted some elk in a long narrow shoot about two miles away. With the 25x eyepieces, we could see antlers on a smaller bull. In the 10×50 binoculars you could see there were elk in the shoot but that was about all. With a pair of 7×35 binoculars the elk were barely visible. Had we not already known they were there, we would never have seen them with the 7x35s. I wish I could have compared the 15×80’s but didn’t have them along at the time.
A little later that same hunting season we were setup and glassing a semi-open hillside at daylight. Before long we spotted three elk about 1500 yards away. Looking through 10 and 15 power binoculars we couldn’t be sure if any of them were bulls. I put the 25x Kowa’s on the elk and could tell immediately, even in that pre-dawn light, that luck was with us. All three were bulls, one was a spike and the other two looked like raghorns or bigger. As it turned out at least one of the bigger boys was a five point, I tipped him over later that morning with a 300 Winchester Mag.
During the summer and early fall, there is a small bunch of whitetails that feed in an 80 acre hay field across the road from my house. With the Kowa’s I can watch them in the evening until it is almost completely dark. They are usually 400-800 yards away. I’m looking to the east at them which helps in the fading light.
What is the upper limit in power? I believe that for general observation it is about 30x. As I mentioned earlier, as power goes up, the field of view goes down. Also, the mirage that target shooters are familiar with can become a problem when looking across a big canyon or the open prairie. Once something is spotted and a closer look is desired, 40x magnification is nice and about the limit in my experience, but not necessary. I’m not much of a variable power fan with spotting scopes. The eyepieces are expensive and often only used in the low to mid power range. With rifle scopes however, I like the big variable Night Force scopes. These scopes have a large 56mm objective, which makes them ideal for use in dim light situations.
There are really only a couple of optical rangefinders that can be considered usable for long-range work. They are the Barr & Stroud manufactured model and the Wild. Baush & Lomb also made one during WWI but it is not as reliable or as easy to use. There are two basic models of the Barr & Strouds. The smaller version, referred to as the 250 model, begins reading ranges at 250 yards. It has a 31.5″ baseline between objectives. The second model is the 500 yard model. As might be guessed, it starts reading distances at 500 yards. It has a longer baseline of one meter. Both models read out to 20,000 yards–farther than any shooter needs.
As I recall, the Wild has a 70mm baseline. The optics in it are of high quality too, like the Barr & Stroud.
The 500 yard model B & S is actually more accurate than the 250 for use over 500 yards. The wider baseline allows it to be a bit more precise.
There are a few variations of these two basic models that I’m familiar with. There are some 250 yard models that are built on the one meter frame. I believe that these were all naval models. Also, there are some 250 models that actually read in meters instead of yards.
The Barr & Strouds are a very high quality optical instrument both physically and optically. They are of 14 power magnification. The image is of such quality that I have used the rangefinder at times as a spotting scope while shooting. In use, two images are seen in the right eyepiece. The upper image is upside-down; the lower, rightside-up. An object, such as a prominent rock or tree, is found in the image. A thumb wheel is then turned which will bring the two images into coincidence. When they are lined up, one on top of the other, the range to the object is read in the left eyepiece. Accuracy is quite remarkable–within about 5 yards at 1000 yards or so. They can be hand-held, but I’ve found that they are easier to use and more accurate if a tripod support is used. The same is true of the big binoculars.
With the naval models, both images are upright.
The Barr & Stroud rangefinders have not been made for many years. Their quality was such that if they had some amount of care, they are still very serviceable after 50 years or so. They are constructed primarily of brass and glass.
Since the militaries of the world have converted to laser rangefinders, no new optical rangefinders are likely to be made again unless a manufacturer feels there is a sufficient demand. The eye-safe laser rangefinder has been developed however. I’ve used the European models, the Bushnell, the North American Integrated Technologies model, and the Lieca 800 and 1200 models. All are good within limitations. The newer Leica models are very lightweight and dependable.
A Leica LAF 800 rangefinder. It operates on one 9 volt battery.
Once the target has been found and ranged, it’s time to launch a bullet at it. To be able to hit that target, a quality target scope is required. It must be of sufficient power so that the target is well defined in the scope image. The image must also be bright enough that the target is visible in poor light conditions. Perhaps the most important aspect of the scope is the reliability of its click adjustments. Long-range shooters don’t hold over their target, they click the vertical adjustment of the scope up the correct amount and hold dead on. Knowing what the `correct’ amount is, was covered earlier. Not all adjustments are what they are supposed to be or what the manufacturer states they are, though.
As an example of the importance of knowing what the click value is worth, I ran a drop chart for a friend recently for his 338-378 Weatherby Mag. He thought the clicks were .25 MOA and that is what I used for the input in the ballistics program. In checking his drop at 1325 yards, he found that he was hitting about 5 feet off the mark. The error was caused by his scope click value not being .25 MOA. It was about .282 MOA, and that difference meant quite a bit at this long distance.
I have used the Leupold target scopes for most of my own shooting and have been satisfied with their performance for the most part. A disadvantage with the standard target models is the limited amount of `up’ adjustment they have. On my 338-378 rifle, I use a 24x Leupold scope with the scope bases milled on an angle, higher in the rear. This gives me more `up’ adjustment but I’m still limited to about 1500 yards with this setup. With a 6.5×20 Leupold on another rifle, 1000 yards is the maximum amount of adjustment I can get. Both are good scopes, but they are lacking in adjustment capability for truly long-range shooting.
Another scope made by Leupold that does have more up adjustment than almost anyone needs is the current Mark 4 model. In the 16x version it has a total of 145 minutes of `up’ adjustment. This is also the only scope I have used that has its click value calibrated for true MOA. That means that one click moves the image in front of the crosshair .262″ at 100 yards, not one quarter inch (.250″) or as is often the case, some other value close to one quarter inch but not quite. It has a unique focusing knob on the left side of the turret housing, opposite of the windage adjustment. This system is very easy to use, and it also eliminates parallax at the focused range. Some might consider 16x as being shy on magnification and I might agree with that for some types of shooting. Dick Thomas can do a power boosts on the 16x Mark 4. We’ll discuss power in more detail a little later.
As I mentioned earlier, I’ve also been using the excellent Night force scopes. My favorite is the 5.5x 22 with the 56mm objective. I’ve been able to see .50 caliber bullets holes at 1000 yards with this model set at 22 power. That is exceptional performance for a rifle scope.
A Nightforce NXS 5.5-22 on a McBros 50 BMG rifle.
The big 2″ Unertl scopes have long been favored by extended range shooters, and with good reason. The advantages include a large 2″ diameter objective lens, comparable to the current crop of 50mm scopes. This size allows for an increase in the exit pupil for a given power, as compared to the more common 40mm objectives. Another advantage is the large range of vertical adjustment in the mount system, allowing the correct amount of adjustment for long-range shots. Also, when a good deal of `up’ is dialed into the scope, the shooter is still looking through the optical center of the lens system. Not so with an internal design. The suspension-type mounting system also handles recoil well.
The Unertl scopes work best with either a barrel bedding block or a long receiver or sleeve. The idea is to keep the scope off the barrel. Because of the length of the Unertl scopes, the only alternative to conventional bedding and a short receiver is to put the front block on the barrel. It has been proven that this can cause unusual vibrations in the barrel and cause flyers. The Unertl scope in the photograph is mounted on the bedding block. The barrel is glued into the block and only the block is bedded into the Lee Six fiberglass stock. The action and barrel float.
Some long-range shooters have said they’ve had poor experiences with internally adjustable scopes because of recoil. They say that the best internal models available just won’t handle the pounding that the big magnum cartridges produce. That hasn’t been my experience, but I don’t doubt that some have had the trouble they reported.
Thinking about this potential problem a little, I wondered just how the recoil of a heavy magnum long-range rifle would compare to a 6PPC 10.5 pound bench rest rifle. To find out, I ran some numbers through a computer program that calculates recoil. I think that most of us would agree that there are no problems with the internally adjustable scopes attributable to recoil on the 10.5 pound rifles.
There are three elements of recoil that add up to a given amount of `kick’. The first is recoil impulse, measured in pounds-second. The calculations for recoil impulse do not involve the weight of the rifle and it is more a measure of the cartridge, perhaps somewhat like measuring horsepower in a car. How the car will perform with that horsepower depends on its weight, gearing, wind resistance, etc. The second ingredient is free-recoil velocity. This is a measure of the speed at which the rifle comes back at the trigger puller, and is measured in feet per second. The third characteristic is free-recoil energy, which is measured in foot-pounds as is bullet energy.
In comparing the recoil of the two rifles, I used a typical 6PPC 10.5 pound rifle firing a 68 grain bullet at 3150 fps from a 27.5 grain charge. Recoil impulse was 1.4 lbs.-second. Free-recoil velocity was 4.4 fps, and free-recoil energy was 3.2 foot-pounds. Most of us are familiar with this amount of kick and wouldn’t consider it excessive by any means.
For the heavy long-range rifle I used as an example a rifle of my own, which is pictured in this article with the Unertl scope on it. It is a tight neck 300 Weatherby that weighs 42 pounds. The load is a 220 grain bullet at 2900 fps from 76 grains of powder. With it I found that the free-recoil velocity is 4.2 lbs.-second. Free-recoil velocity is 3.2 fps (less than the 6PPC) and free-recoil energy is 6.7 foot-pounds (about twice that of the 6PPC).
After shooting both of these rifles one after the other, I find the 300 Weatherby no less uncomfortable to shoot than the 6PPC. I suspect that much of the reason for this is the low free-recoil velocity of the big thirty. I consider both rifles pleasant to shoot.
My point is, I sure can’t see either from the actual felt recoil or from the computer’s numbers that the recoil of the big gun is so punishing that it would tear up an internally adjustable scope. I also know that quite a few big gun shooters are using rifles that weigh considerably more than my 42 pound example. This would even further reduce the recoil. On the other hand, going to a bigger cartridge such as a 30-378 Weatherby or heavier bullets would increase it.
Eric Williams, the former editor of the Fifty Caliber Shooters Association’s magazine VERY HIGH POWER, reports on another potential problem with scopes on muzzle braked rifles. According to Eric some of the brakes on today’s fifties are so efficient that for a moment they are actually pulling the rifle forward. It is a very brief but forceful jolt and it seems as though it puts the scope into a kind of reverse recoil situation. Some of the target type scopes are not designed to take this forward thrust and soon develop loose parts inside. Eric did say that the Leupold Mark 4 seems to hold up, at least so far. It was Eric’s fifty, with a Mark 4 on top, we used to shoot the tank hull at 2000 meters. This rifle had one of the type of brakes on it that can cause the forward thrust I mentioned. The scope seemed to be working just fine for me and it takes a lot of clicking to get on at 2000 meters.
The Night Force scopes have held up well to braked fifties too.
So far we have looked at some of the advantages and disadvantages of internally and externally adjustable scopes. Now we’ll take a look at rifle scope power. Before using the 16x Leupold Mark 4 scope, I considered 20x to be about the minimum magnification for long-range work. I have used 24x scopes for the majority of my own shooting. An experience I had one hunting season caused me to alter my opinion on this a bit, though.
I was elk hunting in an area that had a few open parks, and the elk were using these openings in the early morning and evening hours. We had spotted a cow early in the morning, before the sun had risen over the mountain. A large antlered 6 point bull poked his way into the grassy area soon afterward. I picked him up in the pair of Kowas; he was a splendid bull. We quickly set up the portable bench and sand bags and positioned the rifle. I ranged the bull at 1010 yards through the Barr & Stroud rangefinder. I dialed the correct amount of adjustment into the 24x Leupold scope and found the elk in the small field of view. In the poor early morning light, I had trouble determining which elk was the bull in the scope. We were facing east which didn’t help at all. To find out, I grabbed a pair of 10×50 binoculars that I’d laid down nearby, and with these I immediately could tell the bull from the cow. There was no wind blowing and I was very confident of a lethal hit. I knew my rifle and load well, so hitting a target at this range wouldn’t be difficult. I was getting excited. Just as I reached for a 338-378 Weatherby round to place in the chamber, the big bull stepped into the trees. He never came back out.
I wondered later, if I had been using a scope of lesser power and with a resulting larger exit pupil and brighter image, would I have seen which elk was the bull without going to the binoculars? If I had, I would probably have had plenty of time to fire a shot. The point is, less power may have been better in that situation. The exit pupil of the 24x scope is 1.67mm. A 16x Mark 4 has an exit pupil of 2.5mm, an increase of 50% over the 24x. A 2″ Unertl scope in 24x would be about 2.1mm. In choosing a particular rifle and scope for just paper target work or small varmints, I would want at least 24x. On a rifle that may see some big game hunting however, less may be more.
It seems somewhat ironic to me that I do prefer the 16x to 24x power scopes for long-range work. On several of my 10.5 and 13.5 pound bench rest rifles I have scopes that have been bumped in power by Wally Siebert to 45x. These are used at just 100 and 200 yards. Why then, the lower power for long-range? I suspect that it is the increased field of view. It can be difficult to find a target at long distances with a limited field of view, especially if the target is uphill or downhill.
When clicking a scope knob up or down, it is very important to be able to keep track of where you are from a pre-established zero point. As I mentioned earlier, most shooters use a 100 yard zero as their reference point. The important factor, however, is being able to easily return to zero. In this regard, the Leupold adjustment knobs are superior to the Unertl system, in my opinion. The Leupold knobs have each minute of adjustment so indicated and they have a vertical mark for each click. One revolution is worth 15 minutes and each revolution up reveals a numbered horizontal line on the main body of the adjustment. With this system it is easy to keep track of your zero reference point.
The Unertl system on the other hand is difficult for me to keep track of. I almost have to count each click. The knob is numbered every two clicks, or half minute with conventional 7.2″ spacing. This is not a big complaint, but my philosophy is that simple is better.
There is an alternative to clicking a scope up which some shooters have used successfully. That is to have a multiple dot reticle installed in the scope. The idea is to have a dot or cross wire placed a predetermined distance from another dot. The spacing might be, for example, 10 minutes apart. Another method is to have the dots placed for a certain range. I had Dick Thomas of Premier Reticules set up a 3.5-10 Leupold scope for me with 4 minute diameter dots at 300, 400, 500, 600, 700, and 800 yards. The cross wire is on the 300 yard dot. There is also a 3/4 minute dot above the cross wire for 100 yards. Using a system like this the shooter can also click between dots and gain some precision between dots or extra elevation beyond the last dot.
Earlier we mentioned shimming the rear base to gain `up’ adjustment out of a scope. This principle applies to both internal and external models. Actually a better approach to this, with an internal scope, is to mill the scope bases on an angle. The rear base should be higher. If just the rear base is elevated, as it is when shimming, the scope rings are no longer in line with each other and should be lapped. If both bases are milled together, then the rings will be automatically in line.
It is easy to calculate the correct amount to elevate the rear base. Let’s say that a 24x internal scope has been installed on the rifle. After zeroing the scope at 100 yards we find that two complete revolutions (30 minutes) of adjustment have been `wasted’. We can gain back most of that adjustment by raising the rear of the scope. Thirty minutes of adjustment at 100 yards is about 30 inches. Now, we don’t want to use all of that 30 inches in case we later change loads and find the impact has changed. We may need some of it later. Let’s say that we want 20 inches of it back. So, how much do we want to change the bases?
First we need to know the spacing between the rings. In this example we will call it 6 inches. To find the correct amount to raise the rear ring we divide the 20 inches of elevation we want back by the number of inches in 100 yards (3600). This is then multiplied by the ring spacing in inches (6). This looks like (20/3600) x 6 = .033″. The rear ring should be raised .033″ for the correct adjustment. As mentioned, this same principle applies to Unertl mount systems if the maximum amount of `up’ adjustment is desired. The Unertl scope in the pictures is mounted on a base which has the front mounting area surface ground .075″ lower than the rear.
The long-range shooter has quite a few good choices when it comes to selecting top quality high power binoculars and spotting scopes. With the optical rangefinders, there is really only one suitable choice, the no longer manufactured Barr & Stroud models. Fortunately these are excellent instruments, very well designed and constructed. They can be difficult to find but are indispensable for true long-range shooting. Like scopes and binoculars, there is a fairly good selection of rifle scopes available for accurate long-range work. They will perform their job well if they are carefully chosen for the task and their limitations are recognized. Long-range shooting depends heavily on quality, no compromise optics.
Looking at What can go Wrong
We spotted the cow elk up high in a big semi-open alder patch of probably 20 acres or so in size. She was a long way out, just on the short side of a mile. We were hunting in northwestern Montana near the Idaho line. Soon another cow seemed to materialize in the brush. It had frosted several times early in the season and all of the leaves had dropped off the alders and brush. There was also snow on the ground so we could see into the brush fairly well with our binoculars and spotting scopes. Then behind the second cow came a 5 point bull, his yellow coat giving him away almost as well as his antlers did.
He worked his way down the mountain in our general direction and soon stopped to paw for grass in a small opening. I found him in the 14 power eyepiece of the already mentioned Barr & Stroud rangefinder and ranged him in at 1340 yards. I had my 338-378 Weatherby Mag rifle set up, and when I found him in the scope he was standing broadside. The angle indicator on my rangefinder read about 17 degrees. I had drop figures for 20 degrees and fudged just a bit for the lesser angle. I grabbed one of the big shells and chambered it. There was a slight mist falling from even higher up than the elk and it was coming straight down. I squeezed the trigger and both my spotter and I thought I hit him. The bull flinched a little and jerked his head to look downhill. I thought I had him.
This section will deal with causes for misses and poor grouping at extended ranges. As any experienced target shooter knows, it isn’t always as easy as it looks. This is even more true with long-range shooting. There are some probable causes for shots not going where they were supposed to, though.
Some of the reasons for misses include rifle inaccuracy, incorrect range readings, wind drift, scope zeroing problems, and using the wrong velocity or ballistic coefficient or scope click value on the drop chart. Another possible cause comes from the effects of shooting uphill and downhill. We’ll find out how changes in our rifle, load, scope, and drop calculations can cause a miss at long-range.
Earlier we discussed the building of an accurate long-range rifle but one of the most common reasons for missing a target or for poor grouping at long-range is a rifle that just isn’t up to snuff. Accuracy in this game seems to be like many temporal things in life, you just can’t get enough of it. Actually, we can divide the accuracy problem into two distinct areas, rifle inaccuracy and ammunition inaccuracy.
The heavier a rifle is, generally speaking, the more accurate it is. We can’t expect an eight pound sporter to shoot as well as a 40 pound bench gun. The shooter must decide first, I believe, when building or modifying a rifle for long-range shooting, how much he wants it to weigh when finished. If he plans to walk around with it at all, then probably a 10-15 pound rifle is the maximum weight. It will most likely be closer to 10 pounds, too. If though, he plans to shoot it exclusively from a bench or stand, weight is not much of a consideration. As we said, heavier is better (at least in the accurate gun world) because the component parts are bigger and stiffer. Also, a heavier rifle will have much less recoil. On a lighter weight rifle, a muzzle brake will reduce recoil considerably though.
The rifle must be built around a potentially accurate action with a good trigger. As I mentioned before, I like the custom actions but something like a Remington 700 will work well. If the action will be bedded conventionally then the amount of weight in the barrel must be looked at closely. It is quite possible to bend a commercial magazine-type rifle receiver by hanging 10-15 pounds of barrel from it. Again, the big single shot custom actions are the best for this application. My 338-378 Weatherby Mag, which is shown in the picture, is an example of a big action. It is a single shot and is made from 2″ diameter steel. The barrel threads into the action for almost two inches, too. An action like this will handle a big barrel. Use big actions for big barrels.
An alternative to the big action – big barrel philosophy is the use of a barrel bedding block. The 300 Weatherby in the photograph is built on an unsleeved Remington 700 action converted to single shot with a Davidson ramp. The barrel is 1.450″ in diameter for 30″. It is actually larger in diameter than the action. The barrel though, is epoxied into the block with the action and remainder of the barrel floating. In this example the barrel is glued but some rifles use a split block with the barrel clamped in the block.
If you are going to put weight into a rifle, the barrel is the best place to do it. The larger a barrel is in diameter the stiffer it is. Barrel stiffness or rigidity increases with the fourth power of its diameter. This means that a 2″ diameter barrel is 16 times stiffer than one of 1″ diameter since 2^4 is 16.
Conversely, barrel stiffness decreases with the third power of its length. As an example, a 30 inch long 30 caliber barrel with a 1″ thread shank and 1.450″ in diameter its full length is much less stiff than the same barrel glued into a block. If we compare it to the same barrel mounted in an 8″ long block with a 1/2″ space between the block and action, we are comparing essentially a 29″ long barrel to one 20.5″ long. In this example the blocked barrel is 2.8 times stiffer. That’s right, the difference in rigidity is almost 3 times in favor of the shorter one. Stiffness means, potentially, more accuracy.
The points here to remember are that a barrel increases in rigidity with the fourth power of its diameter and decreases with the third power of its length.
In the big magnum cartridges burning shovels-full of slow burning powder, barrel length means bullet velocity. Bullet velocity means less wind drift and less bullet drop. Decreasing bullet drop and drift probably means increased accuracy but extra barrel length can mean decreased accuracy because of decreased rigidity and an increase in fouling inside the barrel. To some extent, blocking the barrel lets you have your cake and eat it, too.
The rifle stock must be one that is easy to control on the sandbags and be large enough to support the weight of the barreled action. Laminated wood stocks are both pretty and functional or there are a couple of good fiberglass patterns that work well with these big guns. The weight of the stock should be distributed so that the rifle is not muzzle heavy due to a big barrel. Some have added weight to the butt of the stock to counter this tendency.
The above few paragraphs highlight some of the important areas to look at in modifying or rebuilding a long-range rifle. We won’t discuss cartridges, as that was covered pretty well in the beginning of this article and seems to be a topic of ongoing discussion in most firearm publications. A magnum cartridge of some persuasion is the best way to go.
The rifle may be very capable in the accuracy department but is being fed the wrong ammunition. Bullets are extremely important. They must be true match quality bullets if any degree of accuracy is expected. As an example of bullet quality, the 300 Weatherby in the photo is capable of sub .200″ groups at 100 yards with 220 grain Sierra Match Kings seated to the correct depth. With a 200 grain soft point hunting bullet from another manufacturer, the very best it will do is 3/4″ groups. Shooting groups at 100 yards is not always the best test for accuracy with one of these rifles but this example indicates the importance of best quality bullets.
The cartridge must also be loaded with the correct amount of the right powder. For most shooters the fun part of building a new rifle or rebarreling, is load development. I turn the case necks for my serious long-range rifles. I feel that it does help accuracy and as I said, we need all we can get. Pick a good quality bullet first and then find a powder that delivers maximum velocity with minimum velocity variation and good accuracy. Don’t do all of your initial testing at 100 yards either. Usually a load that performs well at 100 yards will also do well farther out, but not always. Shooting paper at 1000 yards can be an eye opening experience with surprises in store. Although not a long-range rifle, I had a heavy varmint 6PPC that shot about the same size groups at 200 yards as it did at 100 yards. Groups in the 3’s and 4’s with an occasional one in the 2’s won’t get you much in 100 yard matches but at 200 yards they look mighty good. Why this barrel behaved that way I can’t say but the proof is on my targets.
Vertical grouping at long-range may be an indication of pressure problems in the load. Changing the charge weight or powder type may cure it, as might trying another bullet weight or seating depth. It could also be an indication of high velocity variation with that charge. We will discuss an example of extreme spreads in velocity a bit later.
Another possible reason for missing a shot way out there is an incorrect range reading. The Barr & Stroud rangefinders really are the only optical rangefinder available to accurately determine distances. They can go out of adjustment though. The farther out an object is, the less accurate these rangefinders are too, and the more difficult it is to correctly bring the images into coincidence. Because it has a wider baseline, the 500 yard model is more accurate than the 250 yard model for distances beyond 500 yards.
I missed a shot at a nice bull elk once because of an error in reading the range to him. I was hunting in the Bitterroot Mountains and there was about 6″ of snow on the ground at my elevation with even more in the higher mountains near the pass. The elk had moved down because of it, and they were relatively easy to spot across the big canyons. I looked over about 40 cows that morning but hadn’t seen a bull other than a spike about 2 miles away. I soon saw another cow and was looking at her through my 10×50 binoculars when, lo and behold, I finally found a bull.
I quickly set up my 250 model Barr & Stroud rangefinder and found the bull in the field of view. He was pawing through the snow for grass in a small opening in the trees of about an acre or so in size. Earlier, at home, I had checked the calibration of the range finder on a power pole a surveyor measured for me at 999 yards. It was right on the mark, and after checking it I left the rangefinder set on 1000 yards. When I put the Barr & Stroud on the bull, he was moving a little as he fed. It looked to me like he was exactly 1000 yards away; I hadn’t adjusted the rangefinder at all. Great, I thought; my scope was already set for 1000 yards, too. I was sure I’d soon have a few hundred pounds of excellent meat on the ground.
I found the elk in my 24x scope and launched a 338 caliber bullet at him from the 338-378. Well, to make a longer story short, I missed. I missed with my second shot too. He didn’t stay in the open after that and with a long face I started putting my equipment away. To be sure I missed, I walked over where he had been. If I had hit him it would have been very clear in the fresh snow. Walking back I wondered why I had missed. Well, it turned out that I’d made an error reading the range to the bull and learned a lesson, I hope. I rechecked the range to a bush that was right where the bull had been standing. It read 960 yards. I had been fooled into thinking the bull was 1000 yards away because he was moving a little when I ranged him and the rangefinder was already set close to what he actually was.
With the bullet and load I was using, the difference in drop between a 960 yard zero and one for 1000 yards is about 25″. I had shot right over his back. For those not familiar with the Barr & Stroud system, it might be hard to visualize how the images are displayed in the eyepiece. Believe me though, it can happen. Take the extra time required to accurately read the range to any target.
That old tricky wind has always been one of the bigger reasons for inaccuracy at extended ranges. When target shooting at long-range, a horizontal dispersion of the shots is a sure indicator that the wind was playing out its hand. It is difficult to judge wind way out there. Mirage is a good indicator and sometimes the only one. I remember looking across a big canyon once while there were a few small cumulus clouds between me and the other side. It didn’t seem like the wind was blowing at all, but those clouds were drifting very slowly left to right. There have been other times when I was hunting and it was snowing. Snow just might be the best wind flag there is. It is easy to see and probably extends all the way to the target. Hopefully it isn’t obscuring the target too much.
If mirage is the only indicator of wind direction it can be difficult to determine exactly which direction the wind is coming from. Usually we can see if it is running from the right or left or boiling, but that is about all. Here is a little tip to determine exactly what direction the wind is blowing from. Looking through a spotting scope on a tripod, rotate the scope around the clock until the mirage is boiling. When it’s boiling you know that the wind is coming either directly at you or blowing away; it should be easy to determine which. Out on the plains country this can be a big help.
With my 338-378 Weatherby load using the original experimental 320 grain Sierra, a 10 MPH direct cross wind blowing the full distance to the target will drift the bullet about 43 inches at 1000 yards. At 500 yards it is less than 10 inches. Other cartridges and bullets will probably drift more, so the wind is definitely a factor. It is for this reason that the heavy bullets for a particular caliber are preferred. The heavier examples have a higher ballistic coefficient and as a result will drift less in the wind. A lighter bullet may drop less, but it will also probably drift more in a breeze. Using the rangefinding and scope adjusting techniques we have discussed in the earlier segments of this article, eliminates most of the problems associated with bullet drop. All this boils down to the fact that it is much easier to determine the distance to an object with a rangefinder and compensate for the bullet drop at that distance than it is to guess how hard the wind is blowing.
For example, if we compare two 30 caliber bullets fired from a long barreled 300 Weatherby our point will be shown. The 168 grain Sierra Match King has a ballistic coefficient of .475 and can be driven at close to 3300 fps in the big Weatherby. The 220 grain Sierra Match King has a ballistic coefficient of .655 according to Sierra. In my experience the BC for the 220 grain bullet is closer to .640 and I use this figure for my drop charts. To see how the wind drift compares, I ran these numbers through a Tioga Engineering ballistics program that computes drop and drift for a 10 mph breeze.
At a muzzle velocity of 3300 fps the 168 grain bullet will blow about 15.5 inches at 500 yards, 38 inches at 750 yards, 75.5 inches at 1000 yards, 130.5 inches at 1250 yards and 206 inches at 1500 yards. The 220 grain Match King will drift 13 inches at 500 yards, 31.5 at 750 yards, 61.5 at 1000 yards, 103 inches at 1250 yards, and 160 inches at 1500 yards. At every yardage the drift for the same 10 mph wind is less for the higher ballistic coefficient 220 grain bullet. The drop for the 168 is less though. About 11.4 inches less at 500 yards, 23.2 inches at 750 yards, 34.7 at 1000 yards, 32.4 inches at 1250 yards (its starting to catch up now) and at 1500 yards, they are just about even (1 inch more for the 220 grain).
If anything, this example is skewed in favor of the 168 grain bullet for two reasons. First we used Sierra’s ballistic coefficient figure for the 168 grain bullet but lowered theirs for the 220 grain bullet. Secondly, going with a 400 fps difference between the two bullets is being a bit generous. In reality, the difference would probably not be quite that great. Giving the 168 grain Match King a 3300 fps muzzle velocity is being a little optimistic.
The point is, a higher BC from a heavier bullet of the same basic shape means less wind drift. It also means more drop, but if we know the exact range to the target, actual drop is not as important as wind drift is. Hence, the high BC bullet is the best choice, provided it is also accurate.
Using Incorrect Velocity
As we mentioned earlier, using the wrong velocity on the drop chart can lead to misses. There are several reasons why the actual muzzle velocities in the field from a proven rifle may be different than expected. Changes in powder lots or types or even primers can have an effect on velocity. They might not always cause a big change, but they can sometimes. Another possible reason is throat erosion. Usually velocity will decrease as a throat moves forward. A load chronographed early in a barrel’s life may not produce the same velocity several hundred rounds later.
Changes in temperature can also affect velocities. With my 338-378 I have checked the velocities for my load from about 30 degrees up to 85 degrees. As an example of what temperature changes can do I’m listing what I found my velocities to be at different temperatures. The powder is IMR 5010 ignited by Federal 215 primers, and the bullet is the experimental 320 grain Sierra Match King. At 29 degrees it averaged 2696 and 2722 fps, at 40 degrees 2717 and 2720 fps, at 50 degrees 2735 fps, 2774 fps at 60 degrees, 2796 fps at 76 degrees and 2802 and 2784 fps at 82 degrees. The trend is obviously an increase in velocity as the temperature goes up. The difference in velocity from the high 20’s to the low 80’s is about 100 fps. That is easily enough to cause a miss at extended ranges if the wrong velocity is used on the drop chart. With this load, a change in velocity of just 50 fps translates into a difference in drop at 1000 yards of about 12 inches and at 1500 yards it is almost 3 feet.
Other cartridges and powders might show a much different picture, but the general trend is for velocities to go up with temperature. It’s best to know what the load in your rifle is producing for the conditions you plan to shoot in.
Ballistic Coefficient Errors
As an example of using the wrong ballistic coefficient, if we use the Sierra 338 Match King in the 338-378 Weatherby and compare C1 ballistic coefficients of .775 and .825 (.050 difference) we find the difference in drop is 7 inches at 1000 yards and 33 inches at 1500 yards. This bullet actually has a BC of about .800.
As we mentioned earlier, ballistic coefficient changes with velocity. When shooting over a long distance the bullet will go through several different velocity ranges. The best way to know where the bullet will hit is to take it out and fire at many distances. It’s fun, too. I frequently take my equipment out into the mountains near my home and shoot at rocks or stumps or bears way out there and compare actual MOA scope corrections to those indicated by the computer printout. By doing so, I can fine-tune my charts for the existing conditions. Coordinating scope clicks with the rangefinder also insures correct scope settings even if rangefinder is out of calibration or the scopes click value is not what it is supposed to be.
Earlier I emphasized the importance of knowing the exact click value of the particular scope being used. Most manufacturers design their adjustments to have a nominal one quarter minute of angle adjustment per click. The problem comes in, however, when the wrong definition of minute of angle is used. One minute of angle at 100 yards is 1.047″. This value is very close to exactly one whole inch, so most people round it to 1.000″. Some of the manufacturers do, too, although they will state otherwise in product literature. Using true MOA, one quarter minute is .262″ at 100 yards, not .250″.
The small difference between .250″ and .262″ may not seem very great, and it isn’t at 100 yards. The problem manifests itself, though, when many clicks are dialed into a scope for long-range use. With a 100 yards zero and then dialing in 25 minutes of adjustment for a 1000 zero, 100 clicks are spun into the scope. The difference between one quarter MOA and one quarter inch is .012″ at 100 yards. At 1000 yards the difference is .120″ or almost 1/8 inch per click. If we multiply that .120″ times 100 clicks, the error is now translated into a full 12″ at 1000 yards. That is too much built in error. If we know exactly how much the clicks of the scope being used are worth however, we can make adjustments to the MOA correction needed.
When discussing scope adjustments, we have stated that most shooters base their drop charts on a 100 yard zero. This does not mean however that the rifle cannot be zeroed at a farther range and the impact point checked against the drop chart. This is in fact a very good idea. I’m sure that not all 100 yard ranges are exactly 100 yards. In fact, I know of one that is exactly 100 meters but most shooters using that range assume that is 100 yards. Experience in the field, firing at targets and paper at long-range, is the best way to learn where a rifle and load will shoot.
Shooting Uphill and Downhill
I can only recall one important shot that I have missed at long-range because of the angle to the target. Again I missed a nice bull elk because of it, and this is the tale that I started this trouble shooting section with.
The bull soon wandered off through the brush, and it was obvious that he wasn’t hit. We could see him moving in and out of the alders for about an hour and his only interest was in eating.
The next morning we hiked up and found the exact spot in which the bull had been standing when I shot. Elk hair was scattered on top of the snow but we saw no blood. I examined the alders a few feet behind his tracks and found where the bullet had clipped off a few branches. The pruned limbs were just at the height of an elk’s back. I didn’t fudge quite right. Had I put one or two less clicks into the scope, I would have taken him.
Well, we learn from our mistakes, sometimes more than from our successes. The point is, shooting at a steep angle can be a bit tricky. A 20 degree angle may not seem very steep, but believe me, it is and the same thing can happen downhill. Earlier we discussed the math involved in uphill/downhill trajectory calculations in detail. The farther away the target is, the more effect the angle has on actual drop.
We can see that there are likely reasons why a shot does not go where it was intended. As we just mentioned angled shooting may be a cause as can the wind. Aside from these two possibilities and rifle inaccuracy, the reason is probably related to a change in bullet velocity, using the incorrect ballistic coefficient, using an incorrect scope click value in calculating MOA corrections, or an error in range measurement.
A few have been critical of long-range big game hunting and one or two have just flat out refused to believe that such nonsense could even be true. To those who don’t believe, I can only say it is true and very possible to hunt at long-range. The heavy 1000 yard target-type rifles used while hunting are capable of tremendous accuracy. A look at some of the record groups, that have been fired during 1000 yard benchrest competition can be seen on another part of our web site, is impressive. Five shot groups under 4 inches are quite possible at 1000 yards.
For those who think it is an unethical way to hunt, I have to wonder if they think hunting of any sort is morally right other than “conventional” hunting? I don’t criticize other forms of big game hunting such as archery, handgun hunting, muzzle loaders, shotgun slugs and buckshot, baiting, or hunting with dogs. So why do they? I can guarantee that my long-range rifles are far more accurate at any range than any of the weapons I just mentioned. The fact that I choose to hunt using the methods my articles have described, with some judgement thrown in, does not make me any less of a sportsman than conventional hunters or those using the other methods I mentioned.
To those who would like to hunt at long-range but have yet to do so, I would like to offer the following. If you want to hunt at long-range, don’t go about it in a half prepared way. Buy the necessary equipment and practice with it on inanimate objects a lot before attempting to go hunting. Learn your equipment and your own limitations and don’t go past them while hunting. It can be fun, frustrating and rewarding. If I have made any contribution to your success then we both will have gained.