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The DARPA XM-3 was an improved variant of the M40A3 sniper rifle designed by DARPA in collaboration with Iron Brigade Armory Ltd. in 2005 and built by the Marine Corps Precision Weapons Shop in 2006.

An experimental project that was never official, the XM-3 attempted to solve all the shortcomings that the M40A3 had.


The M40 had been used by the Marines for many years, but when wars such as 9/11 came around, the shortcomings of the M40 became rather apparent; as a result, the Marines requested a rifle that would be shorter, lighter, be quieter and have a better field of view than the older M40. Urgent Needs Statements were submitted by the sniper platoons on the front lines, with the U.S. Defense Advanced Research Project Agency (DARPA) being the first to respond.

From 2003, DARPA designed a rifle that was able to increase the lethality of snipers in addition to improving their survivability. Development of the rifle started in early 2005, then known as the M40XM1; the rifle was meant to be lighter, shorter, possess a suppressor and night vision capabilities. A total of five configurations of the rifle were penned down before DARPA settled on the final configuration for the rifle.

A total of fifty-two rifles were produced, all hand-built by the Marine Corps Precision Weapons Shop in Quantico, Virginia. The US Marine Corps started to take delivery of the first XM-3s in 2006, just twelve months after the design was penned down. The XM-3 was well received by its users, mainly due to its lighter weight and admirable accuracy even when suppressed.

Unfortunately, a few problems arose with the XM-3 rifles once they saw use. The XM-3 program was never official, and so no structured training or maintenance program was put in place for these rifles; another problem was due to the rifle's optic, which was the same scope as used on the Mk.13 MOD 5 sniper rifles but adjusted in MOA as opposed to MIL adjustments.

Most XM-3s eventually became theater assets, with 48 of them being sent to the Marine Corps Logistics Base in Albany, Georgia; the 48 rifles were slated for destruction in August 2012, but the destruction never came to be. Some time in 2014, all 52 XM-3s were transferred to the U.S. Army, which in turn transferred the rifles to the Civilian Marksmanship Program, where they have been auctioned off to civilians.[1] The rifles are extremely rare now and incredibly sought after, with most fetching five-digit sums.

Design Details[]

While the XM-3 appears rather similar to the M40A3 rifle it is based on, the XM-3 does have a variety of differences, including:

  • Clip-slotted receivers that allowed the reverse-engineered titanium Picatinny rail to fit firmly
  • Use of custom made McMillan A1 stocks
  • Stainless steel magazine boxes being hand-fitted and welded to prevent movement when the rifle was assembled
  • Barreled actions bedded in titanium Devcon and Marine Tex allowing for increased lifespan without loss of torque or consistency
  • Recut chamber to allow it to accept M118LR ammo
  • Internal threads of receiver opened up to 1.07 inches (2.7 centimetres), allowing for a perfectly true alignment with the bolt face and bore dimension
  • 18.5 in (47 cm) barrels

The rifle, when originally manufactured, came with a Hardigg iM3200 storm case, a Surefire FA762SS suppressor with its own soft case, a Nightforce NXS 3.5-15X50 MD day scope zeroed to 1 MOA elevation and MOA wind, a FLIR AN/PVS-22 UNS night vision unit, a Harris bipod, an Eagle cheekrest, a Turner Saddlery AWS sling and a variety of maintenance tools including two T-wrenches, cleaning rod, bore guide, three bore brushes, a torque wrench and a inch adapter.[1]


The rifle uses M118LR 7.62×51mm NATO bullets.


The fifty-two rifles really did not have any variants, although some of the rifles had unique traits; two XM-3s had takedown stocks, while only one XM-3 had a fluted barrel.