The story of the Special Purpose Rifle (SPR) starts with the USSOCOM's Enhanced Carbine Program, from which the SPR was born.

In October 2000, the U.S. Special Operations Command (USSOCOM) issued a Summary of System Descriptions, and in particular, SOPMOD Block 2 and 3 Systems. The USSOCOM includes the U.S. Army Special Forces, U.S. Navy SEALs, Airborne Rangers and U.S. Air Force elements.

Officially called the Special Operations Peculiar Modification Program (SOPMOD), the program centers around what is called the Enhanced Carbine, a project that encompasses an extensive list of requirements for the main battle rifle (MBR) of the future.

These requirements are listed in what is called the SOPMOD Upgrade Block II.

The SOPMOD Upgrade Block II

Consisting of modifications and improvements to the M4A1 carbine, SOPMOD was meant to ensure enhanced reliability, accuracy, zero retention, ergonomics/man machine interface, a reduced cyclic rate and an increased service life of 15,000 rounds. A summary system description includes the following components:

– Enhanced Carbine (the basic weapon).

– Special Purpose Receiver (SPR), a .223 sniper component (now a complete rifle).

– Over The Breech Receiver (OTBR), a wet/underwater capability (a pistol caliber component).

– Close Quarter Battle Receiver (CQBR), a short–barreled version.

– Enhanced Shotgun Module (ESM) for door breaching/less than lethal applications.

– Enhanced Combat Optical Sight (ECOS), a multi–purpose illuminated–reticle sight.

– Image Intensifier Module (IIM), a night vision device (NVD) capable of being used with the ECOS.

– Thermal Image Module (TIM).

– Digital Daylight Image Video Module.

– Rangefinder Module (RM).

– Integrated Pointer–Illuminator Module (IPIM), an improved laser capable of visible and IR operation.

– Heat Source Detection Module (HSDM).

– Battery Recharger/Blasting Machine (BRBM).

– Laser Protection/Protection from Optical Augmentation (LPPOA), a hi–tech filter system.

– Muzzle Brake/Suppressor. The OPS, Inc. sound suppressor was adopted for the SPR.

– Sustained Fire Assembly (SFA), a belt–fed LMG upper for the M4 lower receiver group.

– Chamber Bore Sight (CBS).

– Enhanced Bayonet/Field Knife (EBFK), a new utility knife to attach to the barrel.

– Shot Counter (SC).

– Improved 5.56mm Ammunition.

– Enhanced Grenade Launcher Module (GLM).

– Integrated Carbine (IC), a long–range future alternative to the OICW.

– Sensor Fusion Module (SFM), a sensor fusion imaging/aiming capability.

– Improved 40mm Grenade and Other Enhanced Indirect Fire Munitions (EIFM).

In the original document, accompanying each requirement was a computer–generated drawing of the gun and/or component, some of which were quite recognizable, while others were only conceptually represented. Of particular interest was the basic weapon, which was centered on the M4A1 (M16) Carbine and one subtle, but important requirement included in the summary: This requirement was a marked reduction of mean rounds between failure/stoppage and "barrel assemblies that were more accurate, maintained accuracy longer, and rigidly mounted four–quadrant MILSTD 1913 rails to retain zero within ½ MOA objective/1 MOA threshold." Among other system requirements were ambidextrous controls, folding front and rear iron sights, and a sloping cheek–weld stock with five adjustable lengths.

A key element of the Enhanced Carbine, the above "barrel assembly" took on major importance and sparked competition between several American companies including A.R.M.S., C–More, F.N.M.I., and KAC, all of which designed and built systems that incorporated multiple M1913 rails. Consisting of a rounded metal handguard, the C–More had four fulllength rails and left the barrel free floating. F.N.M.I.'s Floating Integrated Rail Mount (FIRM) was produced in both M16 and M4 versions, and provided three M1913 rails and a mount for the M203 grenade launcher on the bottom. However, the FIRM was never mass–produced, and the two major competitors were Knight Armament Corp. (KAC), of Florida, and A.R.M.S., Inc., of Massachusetts. Coming on the scene almost immediately, KAC submitted its Rail Adapter System (RAS).

The Rail Adapter System

Replacing the M4 Carbine's handguards, the RAS consists of top and bottom halves machined from 7075–T6 aircraft alloy that attach to the barrel nut and the handguard cap at the front–sight base. Held in place by the delta ring, the RAS is also anchored by an additional locking device that is tightened against the barrel nut. The metal RAS contains fourquadrant M1913 rails on which can be mounted any number of optics and accessories. These rails can also be covered by sliding polymer handguard covers if not used to mount accessories. The top rail is more or less a continuation of the rail on the M4's upper receiver. The RAS is in wide use on M4 Carbines in the Military.

The Selective Integrated Rail System

After a decade of development, the A.R.M.S. M1913 rail assembly was first seen in prototype form in 2000. Called the Selective Integrated Rail (S.I.R.) System, this design consists of a free–floating handguard system on a totally rigid frame. The S.I.R. System mounts directly on the M1913 (socalled "Picatinny") rail on the M4A1 receiver beginning just to the rear of the barrel nut. Here it provides its own full–length rail about 4/10" higher than the receiver rail, with a spring–loaded, folding M16A2 rear sight (the A.R.M.S. #40) mounted directly behind it.

Extending forward to the front sight base, the S.I.R. also fans out and down on either side of the barrel to the centerline of the bore. Here it stops with interrupted rails on either side. Attaching to these rails is a synthetic handguard that locks firmly in place. Along these rails are mounting holes for M1913 accesssory rails, and mounting holes are also found along the bottom of the handguard.

In addition to a providing an uninterrupted top–rail mounting platform, the S.I.R. System also leaves the barrel totally free floating. While it closely surrounds the steel handguard cap, it doesn't touch it. This feature not only increases accuracy, but also greatly reduces heat buildup in the barrel, and almost totally eliminates it in the S.I.R. System. Vent holes in the S.I.R. not only prevent fingers from accidentally entering, but also increase the flow of cool air up into the system. The S.I.R. System weighs only about 4 ounces more than the parts it replaces on the M4A1.

Besides not touching the barrel itself, the S.I.R. System also makes it unnecessary for any accessories to contact the barrel. Although the standard M203 40mm grenade launcher can still be mounted on the S.I.R.–equipped M4, the M203 can be equipped with an adapter to quickly mount directly onto the S.I.R. after removing the synthetic handguard. The S.I.R. even contains a means for housing an M203 sight system. Colt produces the M203 mount for the S.I.R. System under license from A.R.M.S. In addition to having been adopted by foreign military establishments, the S.I.R. System is now being used by some special units of the U.S. Military.

The Close Quarter Battle Receiver

With the SOPMPOD Program well underway by 2001, one element of the USSOCOM, the U.S. Navy SEALs, took great interest in the number 4 component, the Close Quarter Battle Receiver (CQBR).

Amounting to a short–barreled version of the M4A1, the CQBR was tested with both 11.5–inch and 10.5–inch barrels. The 10.5–inch version was selected in mid–2001, but will not accept a sound suppressor. Both types were taken into combat in Afghanistan several months later.

The Special Purpose Rifle

Originally conceived as the Special Purpose Receiver, the SPR was a multipurpose precision assault rifle conversion for the Enhanced Carbine created by the Special Forces Group with prototype support from the U.S. Army Marksmanship Unit (USAMU) Shop. However, the designation soon became the Special Purpose Rifle when SOCOM procured a large number of surplus M16A1 rifles, the lower receiver groups from which were used to build the SPR as a complete weapon. Assembled on an ArmaLite M4A1 type flattop upper receiver, the initial SPR used a heavy 416 stainless steel Match 1–in 8" twist barrel by Douglas, Krieger, or Schneider.

Affixed to the flattop upper receiver by a special barrel nut, the barrel is machined to accept the SOPMOD folding front sight made by Precision Reflex, Inc. (PRI). At the rear of the receiver is an A.R.M.S. M16A2 folding rear sight using a torsion spring to automatically spring up into position when released. This sight returns upright even if knocked down, an airborne requirement. Two trigger systems tested by operators were the single stage match full–auto model from Accuracy Speaks, and the two–stage Match Full–auto trigger from Knight's Armament.

Mounted on the initial SPR was a PRI tubular carbon–fiber handguard. Leaving the barrel totally free floating, the handguard was reinforced by a special extended–length Swan sleeve with an A.R.M.S #38 SPR M1913 MilStd rail. Anchored to the flattop receiver, this rigid sleeve reinforced the handguard. The first SPR used the ERGO Grip by Falcon Industries. As with the basic Enhanced Carbine, the SPR used SOCOM's Ops, Inc. SOPMOD sound suppressor along with PRI's M84 charging handle. Called the "Gas Buster," the M84 provided easy access with a scope mounted and deflected gas blast away from the shooter's eyes.

In 2000, some 150 SPR's were produced with the main components being painted tan using baked–on Cal–Guard. The SPR was issued with a special M30 Leupold telescopic sight. Of 3.5– 10X36mm, this 30mm scope also had a mil–dot reticle. The SPR was issued with proprietary 5.56x45mm ammunition developed for the SF by the AMU. Loaded with 77gr. Sierra Match King bullets by Black Hills Ammunition Company, of Rapid City, South Dakota, this round was type classed as the Mk 262 Mod 0. It has made many 600+ yard hits on the enemy in the Global War On Terrorism (GWOT).

Kevin Morehead, American Hero

Just how many hits the SPR has made on our enemies is classified, but the accomplishment of one Special Forces Hero, the late Sgt. Kevin Morehead, tells some of the story. Part of a team of three snipers with 5th Group, Sgt. Morehead and his comrades became pinned down on a hill by a large force of Taliban that outnumbered them roughly fifty–to–one. Using their Ops, Inc. suppressed SPR's, the three snipers were successful in preventing the enemy from taking the hill, but when night came, the Taliban became more aggressive. What they didn't know was that the three Americans had night vision.

Having grown up in the woods of rural Arkansas, Kevin Morehead was a skilled hunter and tactician. He told the other two SF snipers that he was going to descend the hill on the Taliban's left flank. Throughout the night, as Taliban troops moved or stood up to fire up the hill, Sgt. Morehead shot them one by one. In the dark, they were unaware of where the shots were coming from, and gradually began holding their AK–47s above their heads to fire from behind the boulders that covered the slope. When they did, Kevin shot them in the left armpit with the Black Hills 77 grain Open Tip Match (OTM) Mk 262 Mod 1 5.56mm ammunition he was issued.

In the morning, after U. S. fast movers had arrived and killed or captured what remained of the enemy, Sgt. Morehead was credited with having killed scores of Taliban –– including 51 shot in their left armpits. For his actions, Sgt. Kevin Morehead was awarded the Silver Star by President Bush himself, but was later tragically killed during fighting in Iraq. Kevin Morehead was only 33, but his life story is worthy of a movie.

The Mk 12 Mod. 0 And Mod.1 SPR

As with all other new weapons in the military, the SPR became an evolutionary rifle, and in the aftermath of the 11 September 2001 attack on America, an additional quantity of some 300 of these rifles was hurriedly requested by SOCCOM. Initially called the #38 SPR PEQ– 2–2–3, this second run of SPR's used an improved PRI tubular handguard with a reinforced barrel nut, and a redesigned A.R.M.S. #38 Swan Sleeve. It also used a Douglas Premium Match Grade barrel and an improved Leupold Sniper Scope with an illuminated reticle called the M30A2.

A third variation of the SPR designed by Knight's Armament Company (KAC) was also adopted. Initially called the SPR Alternate (SPR–A), this and all previous designations were replaced by the type classification of simply the Mk 12 Model 0 (zero) and the Mk12 Model 1. The Mod. 0 designation was given to both PRI versions of the SPR and the Mod. 1 to the KAC version.

The Mk 12 Mod. 1 differs from the Mod. 0 in that it uses the KAC fulllength Free–Floating RAS (Rail Adapter System) handguard and KAC open sights. The primary night sight of the Mk 12 Mod.0 and Mod. 1 is the PVS–17 with a PRI Hi–Lo mount, and its primary tactical light is the SureFire M9625406. All versions use the Ops, Inc. SOPMOD sound suppressor.

Although existing SPR's are well equipped, a number of new innovative accessories might improve it to the point of developing a new variant.

A Mk 12 Mod 2 SPR?

With the A.R.M.S. M4–length and Mid–Length S.I.R. Systems having been well received, SOCOM had urged Mr. Richard Swan to develop a full–length version. Finally, in 2004, the A.R.M.S. #59M Full–Length S.I.R. System was fi nished. Incorporating all the features of the existing S.I.R. Systems, the #59M was designed to be used with future Mk 12 (SPR) rifles, as well as all full–length versions of the M16 with flat–top upper receivers. Although it is state–of–the–art, the full–length S.I.R. System has been tested on the SPR, but has not yet been adopted or type classed, as no further SPR's have been requested.

However, since the S.P.R. has been an evolutionary (product improved) rifle, and with the continuing need for precision 5.56mm NATO caliber rifles in the GWOT, it is logical that if more of these rifles are needed, yet another improved SPR will be integrated into the system.

Next month, anxious to field test what could be type classified as the "Mk 12 Mod 2," we acquired the components to assemble an SPR with some of the latest and best accessories on the market. In addition to the A.R.M.S. #59M Full– Length S.I.R. System and A.R.M.S. #40 Rear Sight, the upper receiver component was built on the superb Stag Arms MilStd flattop upper receiver. To this, a stainless steel Krieger Match SPR type 5.56x45mm NATO barrel with a 1–in– 9" twist was installed along with a PRI SOPMOD Folding Front Sight, a PRI M84 charging handle and a SureFire M556FA Suppressor Adapter – plus other superior attachments and accessories now available: don't miss it!

Special Purpose Rifle Contacts:

A.R.M.S., Inc.
230 W. Center St., Dept. SOF
West Bridgewater, MA 02379
508–584–7816
(www.armsmounts.com)

Black Hills Ammunition
3050 Elgin St., Dept. SOF
Rapid City, SD 57709
605–348–5150
(www.black–hills.com)

Falcon Ind.
P.O. Box 1060, Dept. SOF
Tijeras, NM 870759
505–281–3783
(www.ergogrips.net)

Knights Manufacturing Company
7750 Ninth St., SW, Dept.,
Dept. SOF
Vero Beach, FL 32968
772–562–5697
(www.knightarmco.com)

Krieger Barrels, Inc.
2024 Mayfield Rd., Dept. SOF
Richfield, WI 53076
262–628–8558
(www.kriegerbarrels.com)

Leupold & Stevens, Inc.
14400 Northwest Greenbriar Pkwy.,
Dept. SOF
Beaverton, OR 97006
503–646–9171
(www.leupold.com)

OPS, Inc.
P.O. Box 377, Dept. SOF
Shingletown, CA 96088
530–474–3777
(www.opsinc.@c–zone.net)

Precision Reflex Inc.
710 Steine Dr., Dept. SOF
New Bremen, OH 45869
419– 629–2603
(www.pri.mounts.com)

SureFire, LLC
18300 Mt. Baldy Cir., Dept. SOF
Fountain Valley, CA 92708
800–828–8809
(www.surefire.com)



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