Accuwasher - Precision Armament AccuWasher Gen2 Shim Kit

This is the only system I use to attach any of my muzzle devices. You have to look up your barrel diameter and thread pitch for the same size of accuwasher. Just remember the heavy grooves are 5 and the thin grooves are 1. After each washer, hand-screw on the device and look at their sight for the additional degrees and washers you need to add