Chambered in 22 ARC(Advanced Rifle Cartridge), this 22 ARC ENDEAVOR(R), equipped with a 20" barrel delivers 22-250 performance out of the lighter weight AR15 (Mk4) platform. Each CMMG(R) ENDEAVOR rifle is purpose-built for long-range performance, with everything from the Magpul(R) MOE(R) rifle stock to the ZEROED(TM) muzzle brake, and every part in between selected for its utility to the avid marksman.