The CMMG AR-15 Sierra .22 Caliber A3 Upper is a complete dedicated rimfire AR-15 conversion upper that maintains compatibility with all the same parts and accessories that fit your full caliber AR's. The 22 Long Rifle conversion bolt, along with the barrel's true 22 LR chamber and proper 1/16" twist rate, make for a truly accurate rimfire AR-15 for inexpensive practice, small game hunting, and introducing young or new shooters to the AR-15 platform. 

CMMG's Sierra rimfire uppers feature many significant improvements over previous designs, enhancing functionality, reliability, and ease of use. Prominent among these improvements are an Anti-Jam Charging Handle, Live Round Extraction ability, and Gas Deflector. CMMG's durable Weapons Armament Surface Protection (WASP) Melonite treatment has been applied to the barrel and surface-hardens the steel, extending barrel service life by reducing friction in the bore and lessening bore surface wear. 

The Sierra upper is ready to drop on to any standard mil-spec lower receiver, all that's needed are a compatible magazine and a pile of 22 LR ammunition to start enjoying some inexpensive and fun time at the range! Compatible with Black Dog Machine and CMMG rimfire AR-15 magazines (not included). CMMG recommends the use of Plated 40 grain High Velocity 22 LR ammunition for optimal functioning. 

Link to parts manufacturer