Mk-12 SPR

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Summary

Country🇺🇸 United States
CategorySniper rifle
ManufacturerColt

Technical specifications

Mk-12 SPR
Fire Rate700 rounds/min.
Caliber5.56 x 45 mm OTAN
Magazine30 rounds
Length950 mm (37.4 in)
Weight4.5 kg (9.9 lb)
Range550 m (1804 ft)

Description

The United States Navy Mk 12 MOD 0/1/H Special Purpose Rifle (SPR) was developed by the Naval Surface Warfare Center Crane Division for US military special operations units, to serve as a designated marksman rifle. The program was influenced by experiences in Somalia, where forces used modified rifles with different optics, ammunition, triggers, handguards, and rail systems.

Proposed initially as the Special Purpose Receiver upper assembly by Mark Westrom of ArmaLite in 2000, working at Rock Island Arsenal, the concept evolved into a standalone Special Purpose Rifle system. The design group included John Noveske and Steve Holland. The SPR was an outgrowth of the desire for a rifle with greater effective range than the M4 carbine but shorter than the SR-25, stemming from both the SOPMOD Block I program and the US Navy SEALs Recon Rifle. Early models were designated SPR, SPR/A, and SPR/B before the weapon was type-classified by the U.S. Navy as the Mk 12. Initial testing in October 2000 addressed weaknesses in the first production, with corrections made for the second production in 2000-2001. The first SPRs were issued in 2002 and the rifle was phased out of service in 2017.

The Mk 12 design is semi-automatic with a full-auto option for emergencies. Upper receivers were initially supplied by Colt, with production also by Diemaco and potentially ArmaLite later. All are flat-topped with either teardrop or round forward assists. Prototype lower receivers used M16A1 or M4A1 types for their full auto trigger groups; the standard trigger adopted was the Knight's Armament Company 2-stage trigger. Barrels are match-grade, free-floating, stainless steel, 18-inch (MOD 0/1) or 16-inch (MOD H) heavy barrels with a 1:7 rifling twist, manufactured by Douglas Barrels or occasionally Noveske, featuring a contour to reduce weight while maintaining rigidity. An OPS Inc. muzzle brake and collar for suppressor alignment are installed. The barrel design aimed to utilize the Mk 262 cartridge, which uses a 77-grain bullet. Stocks seen on SPRs include M16A1 or M16A2 fixed, telescoping M4, and Crane Enhanced types; compatibility exists with any M16 stock system. A free-floating forearm is standard to enhance accuracy.

Handguards used are PRI Gen I, Gen II, or Gen III carbon-fiber tubes, or the KAC M4 Match Free-Floating Rail Adapter System. The different handguards integrate with specific ARMS sleeves. Accessories include PRI or KAC flip-up sights, various Leupold, TS-30, or Nightforce scopes often mounted with ARMS rings on ARMS Swan Sleeves or KAC FF RAS rails. Bipods, typically Harris, are mounted via ARMS throwlever devices. The OPS Inc. 12th Model Suppressor (later Allen Engineering AEM5) threads directly onto the muzzle brake using the collar for alignment.

Early SPR models included the SPR, SPR/A, and SPR/B. The Mk 12 was produced in MOD 0, MOD 1, and MOD H variants.

The variants were used by different forces:

  • Mk 12 Mod 0: US Army Special Forces

  • Mk 12 Mod 1: Rangers, US Navy SEALs, Special Tactical Teams, United States Marine Corps

  • Mk 12 Mod H: Army SOF and Special Mission Units, characterized by a shorter 16-inch barrel and a retrofit upper with PRI Gen3 round handguards and a shorter RECCE rail, replacing the original Swan Sleeve for reduced weight

SPR/A and SPR/B variants specifically used the KAC M4 Match Free-Floating Rail Adapter System and ARMS #22 high rings, differing from the ARMS Swan Sleeve and ARMS #22 medium rings found on the SPR and Mk 12 MOD 0/H.

The Mk 12 SPR was in service with United States Special Operations Forces in the designated marksman role until 2017. Early prototypes were issued starting in 2002, seeing wide deployment during the wars in Iraq and Afghanistan as a designated marksman rifle.