Buy your CMMG Conversion Kits at BattleHawk Armory today! Swapping your bolt carrier group with a CMMG Conversion Bolt Group takes only seconds to install and is piston compatible. This .22 Conversion Kit operates on direct blowback, and do not utilize the impingement tube for function. The Bravo Conversion Bolt Group base model is stainless steel and generally easier to clean. This is the most affordable Stainless Steel CMMG conversion kit. It includes the stainless steel conversion bolt group and a 25-round magazine. All Stainless Steel Construction A 25rd Magazine. Works in most 5.56/.223 chambered rifles.