Originally Posted By PSYWAR1-0:

The Recce platform was something that sprung up within the NSW and 5th SFG communities that first became the Special Purpose Receiver built by Crane, which was supposed to be installed on any M4 lower. After a time when the perfect storm of the users wanting a match-grade trigger and the bolt-bounce issue was identified, the Special Purpose Receiver morphed into a complete rifle that was type-classified as the Mk12.

Mk12: A BRIEF HISTORY (as authored by "LGT" & "FL")

Mk12 Special Purpose Rifle (SPR)

Scoped versions of the M16 rifle existed as far back as the 1960s. Like nearly all historic military rifles, the M16 went through decades of efforts to improve its accuracy, both in the military and civilian marksmanship communities.

The need for the SPR dates back to the late 1980s and early 1990s when the 7.62mm M21 sniper rifle, a semi-automatic weapon of Vietnam vintage, was replaced by the M24 sniper rifle, a bolt action weapon. The M24 was originally specified to be a .300 Winchester Magnum, but the Army decided to field it in 7.62 NATO for a variety of economic reasons. This left the M24 in the unenviable position of being the worst of both worlds in the eyes of snipers at the time, since it lost the fast-shooing, semiautomatic capability of the M21, but did not gain the range advantage of the .300WM. This compromise left a vacant requirement for a fast-shooting semi-automatic sniper rifle. This need was most apparent in the US Army Special Forces (SF) community, since the other commands within the Special Operations Forces structure filled that need with Knights Armament Corporation's SR-25 sniper rifle.

Army SF, being prohibited by its leadership from procuring the SR-25, sought the next best alternative, namely a Special Purpose Receiver (SPR) kit to convert the Army SF M4 carbines into highly accurate rifles. In late 1998, at the request of SFC Steve Holland of 5th Special Forces Group, and the approval of the SOPMOD joint IPT, the Special Operations Peculiar Modifications (SOPMOD) Program Manager, Troy Smith, authorized the purchase of 5 sets of commercial items as an SPR experiment.

The original requirement was for USASOC, mainly the SF Groups, as WARCOM had the MK11, 7.62mm system. Once the SPR requirement was developed and demonstrated through experimentation, most of the other commands in USSOCOM added themselves to the Basis of Issue Plan (BOIP). The USSOCOM requirement for the SPR, with improved ammunition, was approved in July 1999, as part of the SOPMOD Kit, Operational Requirements Document, Version 5 (ORD 5).

Further initial development included several variants of the SPR and new ammunition that were compatible with the M4 carbine's lower receiver. It was found that standard issue M855 5.56mm ammunition was not consistent enough to meet the requirement. In 2000, based on an upgrade requirement to provide a match-grade trigger to the design, Mr. Paul Miller, the SPR project manager, discovered an opportunity to pick through over 15,000 M16A1s that had been sent to Crane for destruction. Realizing that these M16A1 rifles, some of which were virtually new, could be used as "free lumber” to build full SPR weapons, Paul selected several thousand rifles to be set aside for the new SPR project. The SPR underwent a minor but significant name change, with the R having originally stood for "Receiver” now standing for "Rifle"

The new weapon system was worthless without a matching round of ammunition to obtain the performance required. The PEO-SP USSOCOM authorized the new round that became Mk262 as part of the Mk12 system in August 2000. Paul Miller and his SPR team refined the 77-grain prototype ammunition and built approximately 124 SPR Rifles in the summer of 2001. These were finished just in time to ship out to Army SF in late October 2001, to be used in the first invasion of Afghanistan. The SPR rifles were extremely well-received, and the SOF combat units ordered hundreds more.

In May 2002, USSOCOM removed the Mk12 and other complete weapons projects from the SOPMOD Program and placed them under the newly-formed USSOCOM Weapons Program. The fielded weapons included two versions (Mk12 Special Purpose Rifle Mod0 and Mod1). Fielding has since been structured for Mk12 Mod1 Special Purpose Rifle only. This rifle is used by Joint USSOCOM Commands and the USMC in combination with M262 (AA53, 77 grain) ammunition. Formal fielding of the full-rate production version of the Mk12 rifle and ammunition occurred in May 2003 and was completed in FY '04.

In 2012, as the decade of war on terrorism was winding down and the SCAR weapon system began replacing the requirement for the Mk12, USSOCOM and Naval Special Warfare divested themselves of the Mk12 weapons system, and the Mk12 is now being looked at to fill a Designated Marksman Role within Brown Water Navy commands.