Knight’s Armament M110: The New Breed of Sniper Rifle

Over the last 15 or so years, the sniper rifle in both concept and rifle has changed.  It was not until the Vietnam War where a semiautomatic sniper rifle based on the M14 rifle was introduced.  However, it did not perform as well as the bolt action counterpart and required a full time gunsmith to keep it working.  So the semiautomatic rifle was in limited use with the standard still being the bolt action sniper rifle.

However, in the late 1950s a rifle was designed by Eugene M. Stoner at ArmaLite, Inc. called the AR-10.  ArmaLite was a division of Fairchild Engine and Aircraft located in Hollywood, California.  This revolutionary rifle was truly “Tomorrow’s Rifle Today,” that was more true than anyone knew back then.  Although it never had a chance to compete head-on with the M14 for the next U.S. infantry rifle due to Army politics, as well as the deep rooted thought of a rifle having to be made from steel and wood, the AR-10 did get noticed.  During its limited testing it was known to be the most accurate auto loading rifle made as said by the testers from Ordnance Corps.  Limited numbers of AR-10 rifles were manufactured in the Netherlands by Artillerie-Inrichtingen.  They were manufactured for Dutch Army trials as well as sold in limited numbers to some other countries including, Sudan, Cuba, Italy, Guatemala and Portugal.  As predicted, the M14 was adopted and the AR-10 was tossed in the Ordnance Corps scrap heap.  The requirement came down to scale the AR-10 down to a .22 caliber and the AR-15 was born.  The rights were sold for the AR-15 as well as the AR-10 to Colt’s Patent Firearms Manufacturing Company.  Colt went on to produce the AR-15 but ignored the AR-10 design.  That was left for other companies to capitalize on.  To trace the AR-10 lineage to today’s most advanced sniper rifle we must skip ahead nearly 30 or so years ahead to 1991.

In November of 1991, a Mission Needs Statement was drafted for an Enhanced Sniper Support Team Weapon (SSTW).  This was written by Lt. Col. David Lutz while serving as the Program Manager for Infantry Weapons at MARCORSYSCOM at Quantico, VA.  This documentation was an effort to restart a cancelled Designated Marksman Weapon program (DMR) based on the M14 which could not be made to do all the things needed in a logistically supportable package acceptable to the Fleet Marine Forces.  Its requirement document was weak because it totally lacked objectivity in doing a mission analysis or seeking other viable solutions.  At the time, the current SSTW was the M16A2 rifle.  This weapon supported the M40A1 sniper rifle in the two man scout sniper team.  The M16A2 SSTW was used to engage close-up targets and provide rapid fire suppressive fire if needed.  Some noted deficiencies were the M16A2’s poor interface with the soldier when having optics mounted, including night vision.  The current issue M855 ball ammunition did not meet the accuracy specifications of a SSTW.

USMC snipers firing the Mk11 Mod 0 on the range. Note the use of the suppressor as this is commonly used on the rifles in the field.

The enhanced SSTW would fill the role of a 0 to 600 meter intermediate range sniper rifle.  It would have ammunition interchangeability with the M40A1 7.62x51mm sniper rifle and it would have the ability to mount a sound suppressor.  Optics would be mounted in-line with the shooter’s eyes for a comfortable mount.  This rifle will also have to overcome current problems with the unit, direct, general, and depot support problems (availability and maintainability) long associated with the hand-built and Marine Corps customized M40A1.

Lt. Col. Lutz recalls that he knew of (5 each) Dutch NATO AR-10s that were in a bunker at Picatinny Arsenal from when he was stationed there during 1980-83.  So he had one of his successors, USMC Liaison Officer Maj. Dody Knootz, pick out one that shot the best and “temporary loan” it to them at Quantico.  Several modifications were made with the most significant being the carrying handle cut off and a weaver rail attached to the upper receiver.  The AR-10 had some of the improved M16A2 components added to it including the pistol grip and handguards.  All this was to make it look like and use A2 service rifle parts and training.  Additionally, they removed the AR-10’s faux muzzle, which incorporated a grenade launching spigot, exposed its skinny barrel and threaded muzzle.  Lutz recalls sending the upper to Phil Seberger to have a suppressor made & fitted to it.

As recalled by Lutz, as a concept demonstrator it was a success.  “When my general came out to fire it he brought with him his Australian Army Liaison Officer, a full colonel.  My general was reluctant to fire the weapon as I presented it to him, and handed if off to the Australian Colonel.  Offhand, the Colonel hit a steel gong at 100 yards with 20 of 20 shots (suppressed).  When he handed the rifle back to my general, he said “General, this is the finest rifle I have ever fired.”  When the General handed the rifle back to me, he said “Dave, you have a program.”  I guess the rest is history…”  Though the concept was sound, the Marines or big army were not ready for a semiautomatic sniper rifle, at least not yet.  So the AR-10 lay dormant once again until the early 1990s.  Even though the original DMR program failed, the STSW maintained life in the requirement and allowed Rifle Team Equipment builders at Quantico to produce more prototype M14 based variants as “interim measures.”  This eventually took on a “life of its own,” and an M14 based program eventually found traction as the M39 Enhanced Marksman Rifle (EMR).  However, the M39 is one of the weapons being replaced by the Marines recent purchase of M110s.  The M110 was inherently able to meet the STSW requirement for mounting of Night Vision without lose of zero, sound suppressor integration, M16 ordnance maintenance and training commonality, supply system commonality and cross-service weapon commonality.

The name Eugene Stoner, although not as well known as Browning, is just as significant in the history of the gun.  Stoner’s design is the longest service rifle in U.S. military history.  During Stoner’s ArmaLite days his goal was to develop 7.62x51mm weapons.  He was very fond of his direct gas system.  After the M14 was selected, the future was only in the smaller caliber round so Stoner went on to develop other rifles to fire the 5.56mm cartridge including the AR-18 and the Stoner weapon series.  He never quite forgot his AR-10.  In the early 1990s, Stoner went to work with C. Reed Knight, Jr., the president of Knight’s Armament Company.  The union spawned the rebirth of the AR-10.  This would be the SR-25 (Stoner Rifle-25 (15+10)).  This rifle would be an AR-10 but would take on the advancements of the M16A2 rifle and maintain 60% parts compatibility.

Right side of the M110 rifle receiver. Notice the ambidextrous bolt release above the magazine release as well as the ambidextrous safety lever. The U.S. markings are on the magazine well.

Released in the early 1990s, the SR-25 Match Rifle was equipped with a 24-inch Remington 5R match grade barrel – the same barrel blanks used on the M24 sniper rifle.  The heavy barrel was free floating with a fiberglass handguard.  The rifle was equipped with a flat top upper receiver with the Mil-Std 1913 rail and the receivers were made from aluminum extrusions.  The rifle was equipped with a 2-stage match grade trigger.  The bolt carrier group kept with the original AR-10 in that it was chrome plated and it also sported the captive firing pin retainer pin.  These were not mass produced rifles.  The uppers and lowers were mated together and had matching serial numbers to identify them.  They were specifically designed around the 168gr OTM Match cartridge.  Using this factory load, the ogive of the bullet set right on the rifling.  This is something match shooters want to accomplish due to not wanting the bullet to “jump” into the rifling thus maintaining control of the projectile right from the moment of chambering.  The original rifles used the standard “waffle” pattern 20-round magazine and later a steel magazine that looked more like an M16 20-round magazine in appearance.  The SR-25 was sold initially through commercial channels that funded R&D.  Every SR-25 was test fired at the factory and provided with a target.  Knight guaranteed that this rifle would fire 1 MOA or under with factory ammunition.  Gene Stoner would work with Knight up until his death in 1997.

The SR-25 quickly gained its reputation for precision accuracy and reliability and its versatility and benefits were appreciated right away by the special operation forces.  SOCOM liked the idea of having a semiautomatic rifle that held 20 rounds of ammunition and rivaled the M24 and M40A1 bolt action rifles.  They also liked that you could engage multiple targets in less than half the time they could with a manual bolt action rifle.

After more than 40 years, the AR-10 would have its day.  In May of 2000, the U.S. Navy and SOCOM adopted the SR-25 as their new Mk 11 Mod 0.  This would be follow by another contract in 2007 for 9.9 million dollars with the need from the Global War On Terrorism.  The Mk11 had some departures from the original design.  Designed to meet the SOCCOM requirement, the rifle was designed to fire the M118 and M118LR match grade 7.62x51mm NATO ammunition.  The Remington barrel was replaced with an Obermeyer barrel and was shortened to 20 inches and equipped with a mount for a quick detachable sound suppressor also developed by Knight’s Armament Company.  The 11.35-inch Rail Accessory System free floating handguard provided quad Mil-Std 1913 rails enabling attachment of any given number of accessories including night vision, lasers, tactical lights and bipods.  The standard M16A2 stock and pistol grip are used for parts commonality.  A flip up front sight was added to the gas block as well as KAC’s fully adjustable back-up iron sight was added.  The rifle was equipped with 20-round magazines, a Leupold Vari-X mil dot scope with detachable rings and a Harris bipod.  The Mk11 weighs 15.3 pounds unloaded and has an overall length of 45.4 inches.  The Mk11 would see action with U.S. Special Operations troops all over the world.  The weight of the complete Mk11 Mod 0 with the Leupold 3.5×10 scope & SIMRAD adapter, bipod adapter with LM type S Bipod is 13.7 pounds.

Page 1 2