We have been making/using  these in house for years. We have found most hunting rifle barrel profiles need to be threaded to 9/16, but nobody made a shim. These Precision  Ground muzzle shims for the common 9/16-24 barrel threads are laser cut on our in house laser to fit clean to shoulder. This 9/16-24 shim kit comes with 5 shims which we have found is plenty to get any brake timed out properly.