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 Model 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 another 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 (M40A1/A3) is . The Marine Corps plans to replace the M40 with the Mk 13 Mod 7. History During the Vietnam War, the Marine Corps decided they needed a standard sniper rifle. After testing several possibilities, they ordered seven hundred Remington Model 40x rifles (target/varmint version of the Remington Model 700 bolt-action rifle), and gave them the M40 designation. Most had a Redfield 3–9x Accurange variable scope mounted. With time, certain weaknesses, primarily warping of the all-wood stock, became apparent. Sometime in the early 1970s, the USMC armorers at MCB Quantico began rebuilding the original M40s into M40A1s. The process involved, among other improvements, replacing the original wood stocks with McMillan A1 fiberglass stocks, as well as replacing the original 3–9× Redfield variable-power scopes with 10× Unertl fixed-power scopes. The M40 was originally designed by Jack Cuddy and Neill Goddard. The stock featured Wichita sling swivels and a Pachmayr buttpad. The Corps began looking at a replacement for the M40 series in 2004, but did not draft requirements until 2009 while working with SOCOM. The plans for a "21st century sniper rifle" were paused while the Army's results of SOCOM's Precision Sniper Rifle program were finalized in 2013. The Marine Corps eventually decided to continue upgrading the M40A-series and keep the 7.62 NATO round, primarily due to the