Custom SPR MK 12 MOD 1 Upper Receiver Group

The SPR concept is one of many great creations of our nation’s rank-and-file SOCOM subject matter experts. The brilliant application of COTS (commercial off-the-shelf) components to create a cost-effective and superbly successful weapons system is simply unparalleled in our military’s history. MSTN has been building faithful SPR clones since 2002. This upper receiver group starts with a 100% fresh Colt M4 upper receiver. To it has been added MSTN’s own rendition of the SPR barrel, a custom Noveske SS CNC-contoured 18″ rifle length gas barrel you can’t get anywhere else. This 39 ounce, 1×8 three groove barrels’ performance with 50 to 77 grain projectiles will leave nothing to be desired in the accuracy department. The barrel is coated with Graphite Black Cerakote by a factory trained specialist. The feed ramps are gently contoured and then highly polished to ensure no OTM bullet point deformation, no scratches along the bullet jacket from feed ramps, and no bullet concentricity issues as is found with standard feed ramps. Unlike the originals, MSTN does not use surplus M16 A1 bolt carrier groups. MSTN uses new LMT proof round tested, MP-inspected bolts. These bolts, along with their companion Young Manufacturing National Match hard chrome plated bolt carrier and internal parts, all have been Ionbond DLC coated – down to the gas rings. You simply cannot find a superior BCG. Other key components original to the Mod 0 are the KAC Long FF RAS, P/N 21318, the PRI Gas Buster, and the 12th Model Brake and barrel collar (now produced by Allen Engineering). The Mod 0 gas block used is a faithful preproduction of the original by Daniel Defense. The correct KAC flip up front sights, P/N 98474, the Folding Rear Sight, 600 Meter, and P/N 99051-BLK, Folding M4 Front Sight, Black., are available if desired for an additional $390.