Caliber: 5.56 NATO. The XBRN177E2 Carbine reproduction is based on the AR platform that was commonly issued to Special Operations forces during the Vietnam war. All-new parts, polymer CAR buttstock, XM177 flash hider, phosphate bolt-carrier group. Gray-anodized receiver, 12.7-in. barrel with a pinned and welded muzzle device that meets BATFE regulations. Overall length: 34 in. Weight: 5.8 lbs. As of 2022, only available as a build kit, not as a complete rifle.