CMMG Inc Bolt Catch MK3. Using a standard AR-15 bolt catch can create problems with lock back when shooting short round steel shots bolt catches should not be considered an integral part of an AR-15 bolt catch system as a wear item or a functional part of a bolt catch system. Wear your bolt catch in the same location that you intend to fire it not at the front of your receiver. We do not recommend using a bolt catch that has a spring or retention that is welded onto the bolt catch as it will release pinched bolts. Specifications for CMMG Inc Bolt Catch: Manufacturer: CMMG Color: Black Condition: New Package Contents: CMMG Inc Bolt Catch What firearm models does the manufacturer say CMMG Inc Bolt Catch is compatible with? The manufacturer suggests that CMMG Inc Bolt Catch is compatible with CMMG Mk3 AR-15 Kahr Arms MK9CMMG Inc 38CA5E8: Bolt CatchMK3