These are high quality clamp on muzzle brakes used to help reduce recoil by more than 50%. No machining is required, just an allen wrench.

.820" - Fits Remington 26" long heavy barrels, or others with similar diameter muzzles.

.850" - Fits Remington 20" long heavy barrels, or others with similar diameter muzzles.

.925" - Fits DPMS and RRA heavy barrels, or others with similar diameter muzzles.

Machined from 6061-T6511 aluminum, and MIL-A-8625 Type III hardcoat anodized in Matte Black

Designed for .30 caliber, smaller calibers will work, perhaps not as effective.