page_title: M40 rifle
section_title: M40A3
hierarchical_section_title: M40 rifle / Variants / M40A3
caption_attribution_description: English: A shooter and his spotter prepare a shot, Jan. 24, 2011, during the Mountain Scout Sniper Course at Marine Corps Mountain Warfare Training Center, Bridgeport, Calif.
context_page_description: The M40 rifle is a bolt-action sniper rifle used by the United States Marine Corps. It has had four variants: the M40, M40A1, M40A3, and M40A5. The M40 was introduced in 1966. The changeover to the A1 model was completed in the 1970s, the A3 in the 2000s, and the A5 in 2009.
  Each M40 is built from a Remington 700 bolt-action rifle, and is modified by USMC armorers at Marine Corps Base Quantico, using components from a number of suppliers. New M40A5s are being built, and A1s are upgraded to A3s and A5s as they rotate into the armory for service and repair. The rifles have had many sub-variations in telescopic sights, and smaller user modifications. The M40A5 incorporates a detachable magazine and a threaded barrel to allow for the use of a sound suppressor or other muzzle device.
  The original M40 was a military type-classified version of the Remington 700; it was factory-made, and had a one-piece wooden stock. The M40A1 and A3 switched to fiberglass stocks made by McMillan, with new scopes. The trigger pull on both models is 3 to 5 lb.
  The Marine Corps plans to replace the M40 with the Mk 13 Mod 7.
context_section_description: Development of the M40A3 began in 1996 and concluded in 2001, when it was placed into service during Operation Enduring Freedom. It served in Operation Iraqi Freedom and other subsequent conflicts. Though its designation would remain M40A3 until 2009, its exact configuration varied with time. Listed here is a description of the components used in the M40A3.
  Action: The M40 has always been based on the Remington 700 Short Action with .308 bolt face, and this is no different in the M40A3. These actions are tuned by Marine armorers; the trigger guard assembly is manufactured by the DD Ross Company, though several M40A3s use Badger Ordnance trigger guards. In 2007, the Marine Corps began replacing the DD Ross trigger guard assemblies with the M5 detachable magazine trigger guard manufactured by Badger Ordnance.
  Barrel: The barrel is a Schneider 610; 24-inch, 6-groove, 1:12" match-grade heavy barrel.
  Stock: All service M40A3s are based upon the A4 Tactical Riflestock, a benchrest-style fiberglass riflestock made by McMillan Fiberglass Stocks and cast molded in an OD Green color. The action is glass bedded into the stock with aluminum pillars, while the barrel is allowed to "float" (it is attached only to the action), ensuring it is stress free during operation. The stock has adjustable length-of-pull (through a buttstock spacer system) and a Marine manufactured adjustable saddle-type cheekpiece. The stock also has six flush mount sling swivel cups, two on each side front and back and one each on the front and rear underside. One bipod stud is located on the underside of the forend.
  Sling: The Model 1907 sling that has been historically used on M40A3s has been replaced with the Quick Cuff Model Two sling manufactured by Tactical Intervention Specialists.
  Bipod: The M40A3s use a 6–9" Harris notched swivel type bipod, model S-BRM, with a KMW Pod-Loc, which is a push button ratcheting bipod swivel locking mechanism.
  Dayscope: The M8541 Scout Sniper Day Scope is a Schmidt and Bender Police Marksman II LP 3–12×50 modified by Premier Reticles. Starting in 2007, this model replaced the Unertl MST-100 10× fixed day scope. This dayscope is mounted with Badger Ordnance USMC M40A3 34mm scope rings, which use a standard ring in the rear and a wider MAX-50 ring in front. The standard front ring cap is replaced with a SPA-Defense B634 34mm Male Dovetail, as a mounting platform for the Simrad KN200 Night Vision Weapon Sight. The scope and rings are mounted on a DD Ross 30-minute-of-angle lugged Picatinny rail.
caption: Snipers utilize a M40A5 with tripod and suppressor while training at the Mountain Warfare Training Center
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