To help ensure that your Lilja .22 long rifle or .17 HM2 drop-in barrel is properly headspaced we offer a .22 long rifle Go Gauge made by Pacific Precision Tool Grinding. The gauge is ground to a rim thickness of .043″ and it is short enough to use in the shouldered 17 HM2 chamber. The price for this gauge is $45. Order one with your drop-in barrel and there are no extra shipping charges.