United States Navy Mark 12 Mod X Special Purpose Rifle
Encyclopedia
The United States Navy Mark 12 Mod 0/1 Special Purpose Rifle (SPR) is a rifle
in service with United States Special Operations Forces
in Operation Enduring Freedom and Operation Iraqi Freedom
. SPR initially stood for Special Purpose Receiver, but that nomenclature has been replaced as the weapon became a stand-alone weapons system, and not just an add-on upper receiver assembly (part of the proposed SOPMOD
upgrades). The SPR was eventually type classified by the U.S. Navy
as the Mk 12. Note that the weapon was developed by a Navy office (Naval Surface Warfare Center Crane Division
) for SOCOM units, not for use by units that fall under the conventional US Navy.
of both the U.S. Army and U.S. Navy, is a heavily modified light sniper
/designated marksman
variation of the AR-15
/M16
line of infantry weapons, and is chambered for NATO standard 5.56x45mm ammunition. The SPR concept was originally proposed by Mark Westrom, currently president of ArmaLite
, while working at Rock Island Arsenal
. The program was an outgrowth of the desire by both US Army and Navy special operations forces for a rifle with greater effective range than an M4 carbine
but still shorter in length than a standard issue M16A2/A4. The SPR program appears to have grown out of both the SOPMOD Block II program, and the U.S. Navy SEALs Recon Rifle
(a 16" flat-topped M16 carbine). The Naval Surface Warfare Center, Crane Division
expanded on the Recon Rifle.
The exact history of the SPR is unclear, but there appear to be either four or five prime iterations of the weapon, culminating in the most recent Mk 12 Mod 1 version. One progression has four models: SPR Proto 1, SPR Proto 2, Mk 12 Mod 0 and Mk 12 Mod 1. The other progression has five models: SPR, SPR/A, SPR/B, Mk 12 Mod 0, and Mk 12 Mod 1. The specifications in this article follow the second progression.
Different U.S. military service branches appear to typically deploy different iterations of the SPR. Photographs, including both U.S. Department of Defense photographs and privately-obtained photographs, consistently show most U.S. Army Special Forces operators using the Mk 12 Mod 0, while NAVSPECWAR operators and U.S. Army Rangers have been identified as using the Mk 12 Mod 1 version. Limited use was seen with the USMC.
The SPR has been featured prominently both in media photos of the Iraq War and in video games such as the government-created America's Army: Special Forces and in Tom Clancy's Ghost Recon 2
.
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
in service with United States Special Operations Forces
United States Special Operations Forces
United States Special Operations Forces under United States Special Operations Command are active and reserve component forces of U.S. Military...
in Operation Enduring Freedom and Operation Iraqi Freedom
2003 invasion of Iraq
The 2003 invasion of Iraq , was the start of the conflict known as the Iraq War, or Operation Iraqi Freedom, in which a combined force of troops from the United States, the United Kingdom, Australia and Poland invaded Iraq and toppled the regime of Saddam Hussein in 21 days of major combat operations...
. SPR initially stood for Special Purpose Receiver, but that nomenclature has been replaced as the weapon became a stand-alone weapons system, and not just an add-on upper receiver assembly (part of the proposed SOPMOD
SOPMOD
The Special Operations Peculiar MODification kit is an accessory system for the M4A1 carbine and FN SCAR Mk 16/17 used by USSOCOM...
upgrades). The SPR was eventually type classified by the U.S. Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
as the Mk 12. Note that the weapon was developed by a Navy office (Naval Surface Warfare Center Crane Division
Naval Surface Warfare Center Crane Division
Naval Surface Warfare Center Crane Division is the principal tenant command located at Naval Support Activity Crane. NSA Crane is a United States Navy installation located approximately southwest of Bloomington, Indiana and predominantly located in Martin County, but small parts also extend into...
) for SOCOM units, not for use by units that fall under the conventional US Navy.
Background
The SPR, used by Special Operations ForcesUnited States Special Operations Command
The United States Special Operations Command is the Unified Combatant Command charged with overseeing the various Special Operations Commands of the Army, Air Force, Navy and Marine Corps of the United States Armed Forces. The command is part of the Department of Defense...
of both the U.S. Army and U.S. Navy, is a heavily modified light sniper
Sniper
A sniper is a marksman who shoots targets from concealed positions or distances exceeding the capabilities of regular personnel. Snipers typically have specialized training and distinct high-precision rifles....
/designated marksman
Designated marksman
The designated marksman is a military marksman role in a U.S. infantry squad. The term sniper was used in Soviet doctrine although the soldiers using the Dragunov were the first to use a specifically designed designated marksman's rifle. Sniper is also used in Russian doctrine...
variation of the AR-15
AR-15
The AR-15 is a lightweight, 5.56 mm, air-cooled, gas-operated, magazine-fed semi-automatic rifle, with a rotating-lock bolt, actuated by direct impingement gas operation. It is manufactured with the extensive use of aluminum alloys and synthetic materials....
/M16
M16 rifle
The M16 is the United States military designation for the AR-15 rifle adapted for both semi-automatic and full-automatic fire. Colt purchased the rights to the AR-15 from ArmaLite, and currently uses that designation only for semi-automatic versions of the rifle. The M16 fires the 5.56×45mm NATO...
line of infantry weapons, and is chambered for NATO standard 5.56x45mm ammunition. The SPR concept was originally proposed by Mark Westrom, currently president of ArmaLite
ArmaLite
ArmaLite is the name of a small arms engineering facility founded in the early 1950s, and once associated with the Fairchild Engine and Airplane Corporation. ArmaLite was formally incorporated as a subdivision of Fairchild on October 1, 1954...
, while working at Rock Island Arsenal
Rock Island Arsenal
The Rock Island Arsenal comprises , located on Arsenal Island, originally known as Rock Island, on the Mississippi River between the cities of Davenport, Iowa, and Rock Island, Illinois. It lies within the state of Illinois. The island was originally established as a government site in 1816, with...
. The program was an outgrowth of the desire by both US Army and Navy special operations forces for a rifle with greater effective range than an M4 carbine
M4 carbine
The M4 carbine is a family of firearms tracing its lineage back to earlier carbine versions of the M16, all based on the original AR-15 designed by Eugene Stoner and made by ArmaLite. It is a shorter and lighter variant of the M16A2 assault rifle, with 80% parts commonality.It is a gas-operated,...
but still shorter in length than a standard issue M16A2/A4. The SPR program appears to have grown out of both the SOPMOD Block II program, and the U.S. Navy SEALs Recon Rifle
SEAL Recon Rifle
Built in-house by U.S. Navy SEAL Team armorers, and later by the Naval Surface Warfare Center, Crane Division , the SEAL Recon Rifle was developed to provide SEAL snipers with a portable, lightweight system with greater lethality than a standard M4 carbine...
(a 16" flat-topped M16 carbine). The Naval Surface Warfare Center, Crane Division
Naval Surface Warfare Center Crane Division
Naval Surface Warfare Center Crane Division is the principal tenant command located at Naval Support Activity Crane. NSA Crane is a United States Navy installation located approximately southwest of Bloomington, Indiana and predominantly located in Martin County, but small parts also extend into...
expanded on the Recon Rifle.
The exact history of the SPR is unclear, but there appear to be either four or five prime iterations of the weapon, culminating in the most recent Mk 12 Mod 1 version. One progression has four models: SPR Proto 1, SPR Proto 2, Mk 12 Mod 0 and Mk 12 Mod 1. The other progression has five models: SPR, SPR/A, SPR/B, Mk 12 Mod 0, and Mk 12 Mod 1. The specifications in this article follow the second progression.
Different U.S. military service branches appear to typically deploy different iterations of the SPR. Photographs, including both U.S. Department of Defense photographs and privately-obtained photographs, consistently show most U.S. Army Special Forces operators using the Mk 12 Mod 0, while NAVSPECWAR operators and U.S. Army Rangers have been identified as using the Mk 12 Mod 1 version. Limited use was seen with the USMC.
The SPR has been featured prominently both in media photos of the Iraq War and in video games such as the government-created America's Army: Special Forces and in Tom Clancy's Ghost Recon 2
Tom Clancy's Ghost Recon 2
Tom Clancy's Ghost Recon 2 is the third console installment in the popular Ghost Recon tactical shooter video game series, published by Ubisoft. It is a sequel to Tom Clancy's Ghost Recon....
.
Specifications
- Upper ReceiverReceiver (firearms)In firearms terminology, the receiver is the part of a firearm that houses the operating parts. The receiver usually contains the bolt carrier group, trigger group, and magazine port. In most handguns, the receiver, or frame, holds the magazine well or rotary magazine as well as the trigger mechanism...
: The majority of the SPR upper receivers were initially supplied by ColtColt DefenseColt Defense LLC, together with its subsidiaries, is a designer, developer and manufacturer of small arms weapons systems for individual soldiers and law enforcement personnel. It is headquartered in West Hartford, Connecticut...
, with others being produced by Colt CanadaColt CanadaColt Canada is a firearms manufacturer owned by US based Colt and located in Kitchener, Ontario, Canada.The company is a defense contractor that manufactures and supplies small arms to the Canadian Forces and Canadian law enforcement agencies, as well as defense research & development, training,...
(then Diemaco). Colt had been outsourcing parts of its production to Diemaco for several years, then purchased Diemaco in February 2005. It is unclear whether the upper receivers for the later SPRs came solely from ArmaLite, or were a mix of receivers from ArmaLite and Colt/Diemaco. All of these upper receivers are flat-topped, but have been seen with either the old-style teardrop forward assistForward assistThe forward assist on a rifle is a button found commonly on M16 and AR-15 styled rifles, usually located near the bolt closure, that when hit will push the bolt carrier forward, ensuring that the bolt is locked. In order to ensure that the extractor is clipped around the rim of the shell, the...
or the newer round style.
- Lower Receiver: When the SPR program was still just an upper receiver assembly (and not a complete rifle), Crane assembled all of its prototypes using either M16A1 or M4A1 lower receivers. It is unknown whether this pattern continued as the rifle evolved. There is also some issue about whether, when the Navy type-classified the weapon, Precision Reflex Incorporated (PRI) began assembling the rifles themselves. While a number of trigger options were tried in the end, the Knight's Armament CompanyKnight's Armament CompanyKnight's Armament Company is an American firearms and firearms parts manufacturer.It is owned by C. Reed Knight and based in Titusville, Florida. KAC is best known for producing the Rail Interface System and the Rail Adapter System grips for military firearms...
(KAC) 2-stage trigger was finally decided upon as the standard.
- Barrel: An 18-inch (457 mm) threaded-muzzle match-grade free floating stainless steel heavy barrel with a 1:7 (178 mm) rifling twist ratio is standard for the SPR. The barrels are manufactured by Douglas Barrels with a special contour to maximize accuracy and to minimize weight. An OPS Inc. muzzle brakeMuzzle brakeMuzzle brakes and recoil compensators are devices that are fitted to the muzzle of a firearm or cannon to redirect propellant gases with the effect of countering both recoil of the gun and unwanted rising of the barrel during rapid fire...
and collar (to align the OPS Inc. 12th Model SuppressorSuppressorA suppressor, sound suppressor, sound moderator, or silencer, is a device attached to or part of the barrel of a firearm which reduces the amount of noise and flash generated by firing the weapon....
) is installed with the barrel. These barrels were designed to take advantage of the new Mk 262 cartridgeCartridge (firearms)A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
, which uses a 77-grain (5 g) bullet.
- Buttstock: SPRs have been seen with M16A1 or M16A2 fixed buttstocks, telescoping M4 buttstocks, and the Crane Enhanced telescoping buttstock. The rifles are compatible with any type of stock system developed for the M16.
- Handguards: In all cases a free-floating forearm is used, which does not touch the barrel directly. This increases the accuracy of the weapon by removing vibration and pressure exerted on the barrel by the rest of the gun. The first SPRs used PRI Gen I or Gen II carbon-fiber free-float tubes. The SPR/A, SPR/B, and Mk 12 Mod 1 all use the Knights Armament Company M4 Match Free-Floating Rail Adapter System. The Mk 12 Mod 0 uses PRI Gen III free-float tubes. The Gen I and Gen II Freefloat Forearms are combined with the Atlantic Research Marketing Systems #38 SPR MOD Sleeve, while the Gen III Freefloat Forearm, due to its it larger barrel nutBarrel nutA sex bolt, also known as a barrel nut, barrel bolt, Chicago screw or post and screw, is a type of fastener which has a barrel-shaped flange and protruding boss that is internally threaded. The boss sits within the components being fastened, and the flange provides the bearing surface...
, only works with the ARMS #38 SPR PEQ-2-3.
- Sights: The original SPR used an early PRI flip-up front sight with an elevation dial, which has since been discontinued. The Mk 12 Mod 0 uses the current PRI flip-up front sight. The SPR/A, SPR/B, and Mk 12 Mod 1 use the KAC rail foreend flip-up front sight. The SPR and Mk 12 Mod 0 use the ARMS #40 flip up rear sight. The rest of the models use the KAC 600 meter flip up rear.
- Optics: Due to the relative modularity of the system, optics (as well as almost everything else) can be mounted according to the operator's wishes. However, SPRs are most often seen with a 3.5–10×40 mm Leupold LR M3 (SPR/A), a 2.5–9×36 mm TS-30 (SPR/B), or a 3–9×36 mm TS-30 A2 (Mk 12 Mod 0/1) Mid Range/Tactical Illuminated Reticle Dayscope. Night vision devices can also be attached. These scopes usually come with flip open dust covers and a honeycomb anti-glare anti-reflection device. Given Nightforce Optics' NAVSPECWAR contract, it is believed that many NAVSPECWAR issued SPRs will use the Nightforce 2.5-10x24 NXS scope.
- Mounts: A long accessory rail, called a SWAN Sleeve (ARMS SPR MOD or ARMS #38 SPR PEQ-2-3), manufactured by ARMS, is installed, running the length of the rifle. The SPR/A and SPR/B both used the KAC M4 Match FF RAS. Two ARMS #22 Throwlever 30 mm steel rings are used to mount the dayscope. The SPR/A, SPR/B, and Mk 12 Mod 1 use ARMS #22 high rings, while due to the increased height from the SWAN Sleeve, the SPR and Mk 12 Mod 0 use ARMS #22 medium rings. An under-the-handguard ARMS #32 Throwlever mount is used to mount the Harris bipod (the ARMS #42 Throwlever mount is used to mount the Versa-Pod); this features a quick release action.
- Bipod: Originally Versa-Pods (a cheaper Chinese-made copy of the relatively expensive Parker-Hale swivel bipod) were used, but were taken off the system after the initial SPR. Currently, a Harris swivel model bipod is typically used with the SPR, and is sometimes seen with a KMW Pod-Loc tension adjustment device. As mentioned above, the bipod is mounted via a ARMS #32 throwlever device attached to the bottom rail of the rifle's forearm. The ARMS mount is used on both the Mod 0 and Mod 1.
- Suppressor: The OPS Inc. 12th Model SPR Muzzle Brake Suppressor threads directly onto the OPS Inc. muzzle brake and uses the collar to stay centered.
- Ammunition: The SPR is not used to fire standard issue 5.56mm M855A1 or M193 ball or M856 tracer ammunitionAmmunitionAmmunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...
. Due to the limits in terminal performance and relatively poor accuracy of the 62-grain (4 g) M855 ball, the Mk 262 Open Tip Match (OTM) round was developed as a more accurate round for the SPR, and manufactured by Black Hills AmmunitionBlack Hills AmmunitionBlack Hills Ammunition is an American ammunition and reloading supplies manufacturing company based in Rapid City, South Dakota. Black Hills is popular among Cowboy Action Shooters because they produce quality ammunition in a number of obsolete calibers, such as .44 Russian, .38 Long Colt, .44-40...
. The first production batches were designated Mk 262 Mod 0 and used a Sierra BulletsSierra BulletsFounded in 1947 in California, Sierra Bullets is an American manufacturer of bullets intended for firearms. Based in Sedalia, Missouri since 1990, Sierra manufactures a very wide range of bullets for both rifles and pistols. Sierra bullets are used for precision target shooting, hunting and defense...
MatchKing 77-grain (5 g) Hollow Point Boat Tail bullet without a cannelure (crimping groove). Black Hills then approached the NoslerNoslerThe name Nosler applies to a number of companies involved in the manufacture of ammunition and handloading components, specializing in high performance hollow point and soft point hunting bullets. Current companies include Nosler, Inc., Nosler Custom, and Nosler Reloading...
bullet manufacturing company, who made a similar 77 gr OTM bullet, and Nosler agreed to supply cannelured bullets to Black Hills. The newer load was designated Mk 262 Mod 1. Recently, Sierra added a minimal crimp to its bullet, and this has since replaced the Nosler bullet in the current versions of Mk 262 Mod 1.
See also
- SR-25SR-25The SR-25 is a semi-automatic sniper rifle designed by Eugene Stoner and manufactured by Knight's Armament Company. The SR-25 uses a rotating bolt and a direct impingement gas system. It is loosely based on Stoner's AR-10, rebuilt in its original 7.62×51mm NATO caliber...
- M110 Semi-Automatic Sniper System
- United States Army Squad Designated Marksman RifleUnited States Army Squad Designated Marksman RifleThe United States Army Squad Designated Marksman Rifle is a heavily modified M16-series semi-automatic rifle intended to provide increased accuracy over range, giving infantry squads greater firepower.-Background:...
- U.S. Marine Corps Squad Advanced Marksman RifleU.S. Marine Corps Squad Advanced Marksman RifleThe Squad Advanced Marksman Rifle is a semi-automatic rifle developed by and in service with the United States Marine Corps. It gives Marines the capability to provide precision fire in support of the rifle squad, providing precision fire in support of an assault, and aid in observation and...
- U.S. Marine Corps Designated Marksman RifleU.S. Marine Corps Designated Marksman RifleThe United States Marine Corps Designated Marksman Rifle is a semi-automatic, gas-operated rifle chambered for the 7.62x51mm NATO cartridge...
- Marine Scout Sniper Rifle