XM109 Anti-Materiel Payload Rifle (AMPR)
Objective Sniper Weapon

The XM109 Anti-Materiel Payload Rifle, commonly referred to just as the Payload Rifle and known initially as the Objective Sniper Weapon, is a short recoil semi-automatic 25mm precision rifle. The prototype rifles featured a MIL-STD-1913 accessory rail for optics, a rear grip, rear monopod socket, detachable bipod and carry handle, and a 5-round detachable box magazine. The weapon was equipped with dual chamber detachable muzzle brake. It was expected that the weapon could be fitted with a sound suppressor.

Dervied by Barrett Firearms Manufacture ring, Inc. from the Model 82 series .50 caliber rifle, the XM109 had accuracy, lethality and Barrett reliability. Based on the proven Model 82/M107 battlefield performance, the Barrett operating system had been shown to be one of the most reliable weapons in the sand, mud, dirt and harsh field conditions experienced by troops in Bosnia, Somalia, Afghanistan, and Iraq. The XM109 weapon provided high parts commonality with the Model 82 series, including the US Army's M107, with most replacement parts already in the logistic system. It had the same approximate weight, about 33 pounds, with the .50 caliber rifles. At 46 inches long overall it was 10 inches shorter. It was hoped that the XM109 would continue the Barrett contribution to the war fighting assets of the military arsenal.

Providing light fighters with armor piercing lethality out to 2,000 meters, the XM109 would allow soldiers to engage and mitigate enemy light armor cost effectively. The XM109 was intended to use the self-same 25x59mm armor-piercing ammunition as the Objective Crew-Served Weapon, which later became the Advanced Crew Served Weapon, the 25mm component of which as designated as XM307.

The XM109 offered significantly greater lethality than .50 caliber rifles, such as the Barrett Model 82 series of the M107, particularly against C4I SAR targets. Near term potential from optimizing the 25mm warhead promised penetration over 1.5 inches of RHA at 1,200 meters and beyond. Long Term optimized ammunition was hoped to offers 2 or more inches of HHA penetration.

The .50 caliber Barrett Model 82 series, including the M107, produced modest recoil energy. The operating mechanism in these weapons, which featured a recoiling barrel assembly, combined with an efficient muzzle brake reduced recoil energy to about 36 foot-pounds. The 25mm XM109 fired ammunition with essentially the same impulse as .50 caliber ammunition. However, the 25x59mm cartridge launched a much heavier projectile and uses much less propellant. The small amount of propellant limits the muzzle brake effects. As a result, the recoil energy of the XM109 exceeded 60 foot pounds.

The requirement for a 20-25mm anti-materiel rifle first appeared in the special operations forces community in the 1990s, following experiences in Operation Desert Storm. US Special Operations Command put out Directive 70-2, a general directive for the development of a heavy anti-materiel rifle in 1992. A Joint Operational Requirements Document for a Heavy Sniper Rifle was approved on 16 March 1994. The Objective Sniper Weapon was developed as a unique "payload" gun designed specifically to interdict special operations forces material targets: such as C4I SAR equipment, support facilities, light vehicles, and crew-served weapons.

The findings of a weaponeering study conducted by the Joint Service Small Arms Program were released in 2002. The test compared the number of rounds fired from a prototype Objective Sniper Weapon to the number fired from a Barrett M82A1 rifle required to disable either a "Big Bird" radar van or a BMP-3 infantry fighting vehicle. At 600 meters, each weapon required the same number of rounds to disable the radar van. At 800 meters, the Objective Sniper Weapon required half as many rounds as the .50 caliber M82A1 to disable to van. At 600 meters, the .50 caliber M82A1 required 2.5 times more rounds than the Objective Sniper Weapon to disable the BMP-3. At 800 meters, the .50 caliber M82A1 required 2 times more rounds than the Objective Sniper Weapon to disable to vehicle.

As of early 2004, the XM109 was being refined under contract to reduce recoil and enhance performance. At that time, the program was on track to field 10 prototype weapon systems in August 2004. The XM109 with the Barrett Optical Ranging System (BORS) could be in full rate production in 90 days from ARO pending limited safety release in August 2004.

The weapon system included the BORS to provide accuracy to engage vehicular targets out to 2,000 meters. It would also accept a full range of other sighting systems (conventional scope, night vision, thermal, red dot). Armor piercing and target practice ammunition was available. Initial tests indicated in excess of 1.5 inch penetration of armor at 500 meters. Breeching capabilities on fortified doors, windows and walls without exposing soldier to enemy fire. There was a potential of ammunition development for riot and crowd control and less lethal applications (rubber projectile, chemical agent, marking). A soft mount was available for watercraft, aircraft, and vehicles. The system was capable of quick modification, within 6 months, to use the air burst ammunition developed for the Objective Crew Served Weapon. The BORS on-board computer had capability to provide targeting information.

By 2006, development of the XM109 had been grouped together as part of a broader Anti-Material Rifle Congressional Program, along with a lightweight variant of the M107, a semi-automatic bullpup rifle from Barrett designated the XM500, and an individual 40x53mm grenade launcher developed by FN Herstal. Cape AeroSpace also demonstrated mechanical to electrical energy conversion using piezoelectric crystals in gas and recoil operated weapon systems as part of the program.