Centurion Arms MK12 5.56 NATO 18" AR-15 Rifle

The MK12 rifle was one of the beginning stages of "enhanced carbine" concept. The original designation as SPR was intended to mean Special Purpose Receiver but the system was eventually type classified by the Navy as a standalone rifle and designated MK12 Mod 0/.1. The concept started with the idea of having a sniper/designated marksman upper receiver for a special operator's standard M4 lower receiver but during initial testing and limited fielding Naval Surface Warfare Center, Crane Division delivered the upper receiver with their own lower so the testing units would not have to deplete the units operational weapons to support the testing. The lowers supplied were mostly M-16A1 lowers with Knights Armament match triggers installed and fixed butt stocks. Specifications: Centurion Arms 18" MK12 5.56mm stainless match air gauged barrel with 1 in 7" twist (blasted stainless finish) Upper receiver is a standard forged Mil-Spec with M4 extended feed ramps Centurion Arms low profile MK12 ga