Science Fair Project Encyclopedia
Each weapon is hand-built by USMC armorers at Marine Corps Base Quantico, using components from a number of suppliers. New A3s are being built, and A1s are upgraded to A3s as they rotate into the armory for service and repair.
|Caliber||7.62 mm NATO (.308 Win)|
|Weight||6.57 kg (14.45 lb)||7.5 kg (16.5 lb)|
|Overall Length||1.117 m (43.97 in)||1.124 m (44.25 in)|
|Barrel Length||610 mm (24 in)|
|Barrel||(to be done)||Schneider Match Grade SS #73|
|Lands and Grooves||6||(to be done)|
|Twist||Right Hand, 1:12||(to be done)|
|Trigger Pull||3 to 5 lbf (13 to 22 N)|
|Magazine Capacity||5 rounds|
|Sight||Unertl 10x with Mil-Dots and BDC;
specially designed for USMC
|Stock||McMillan fiberglass||McMillan Tactical A4|
|Max Effective Range||915 m (1000 yd)|
During the Vietnam war, the Marine Corps decided they needed a standard sniper rifle. After testing several possibilities, they ordered 700 Remington Arms  Model 40x rifles (target/varmint version of the Model 700 bolt action rifle). Most had a Redfield  3-9 power 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 tweaks, replacing the original wood stocks with McMillan fiberglass stocks as well as replacing the original Redfield scopes with Unertl  scopes.
The US Army also uses the Remington 700/40x action as the basis for its M24 SWS (Sniper Weapon System). The primary difference between the two rifles is that while the USMC M40/A1/A3 utilizes the short action version of the Remington 700/40x (designed for shorter cartridges, such as .308 Winchester, 7 mm/08 Remington, .243 Winchester), the Army M24 uses the long action version of the same rifle (designed for full-length cartridges, such as the 30-06 Springfield, and "short" magnum cartridges, such as the 7 mm Remington Magnum, .300 Winchester Magnum and .338 Winchester Magnum). The US Army reasoning behind this decision was to allow them to reconfigure the rifle in the larger, longer-range calibers if necessary. Whether or not they will do this is anyone's guess, but one might note that the British Royal Marines, among others, have adopted rifles in .300 Winchester Magnum and .338 Lapua as special purpose sniper rifles.
Development of the M40A3 began in 1996, and the final product was revealed in 2001. Since then, numerous minor changes have occurred to the platform. It is highly possible that more changes will occur to the platform as it gains operational use in Iraq and Afghanistan. Listed here is the latest configuration known to be used in an M40A3.
Action - The M40 has always been based on the tried and trued Remington 700 Short Action (as opposed to the Long Action in the M24), and this is no different in the M40A3. These actions are all chambered in 7.62x51mm NATO and are house tuned by Marine armorers; the trigger guard assembly is manufactured by the DD Ross Company, though several M40A3s use Badger Ordnance trigger guards.
Barrel - The barrel is a Schneider 24" (25") 5-groove 1:12" match-grade heavy barrel.
Stock - All service M40A3s are based upon the A4 Tactical Riflestock, a high-quality 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 maximum accuracy. The stock has adjustable length-of-pull (through a buttstock spacer system) and an adjustable saddle-type cheekpeice.
Dayscope - An official daytime telescope has not yet been determined for the M40A3. So far, all of these rifles have been equipped with the Unertl 10x40mm scopes that were issued with the M40s and M40A1s, except that they have been refurbished and upgraded by US Optics for proper use on the M40A3's 30 MOA-forward cant Badger Ordnance mount base. However, plans for a acquiring a new variable power scope with a 30mm main tube has been proposed. The dayscope is mounted with Badger Ordnance Maximum scope rings, with a standard ring in the rear, and a wider MAX50-brand ring in front, to allow for the mounting of a Badger Ordnance ringcap (enabling the mounting of SIMRAD add-on night vision devices).
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