- .276 Pedersen
Infobox Firearm Cartridge
name= .276 Pedersen
caption= En-bloc clip loaded with 10 rounds of .276 Pedersen. Image from John Pedersen patent.
service= 1923-1932 (experimental)
case_type= Rimless, bottleneck
primer= Large rifle
balsrc= The .276 Pedersen (7 x 51 mm) round was an experimental 7 mm cartridge developed for the U.S. Army and used in the
Pedersen rifleand early versions of what would become the M1 Garand rifle.
1923in the United States, it was intended to replace the .30-06 Springfieldin new semi-automatic rifles and machine guns. When first recommended for adoption, M1 Garand rifles were chambered for the .276 Pedersen, which held ten rounds in its unique en-bloc clips. The .276 Pedersen was a shorter, lighter and lower pressure round than the .30-06, which made the design of an autoloading rifle easier than the long, powerful .30-06. The US Army Chief of Staff Gen. Douglas MacArthurrejected the .276 Pedersen Garand in 1932after verifying that a .30-06 version was feasible.
History and Technical Notes
Pedersen's round fired a true 7 mm (0.284 in) bullet. Comparable to the contemporary Italian 6.5 x 52 mm (0.264 in)
Carcanoor the Japanese 6.5 x 50 mm(0.264 in) Arisaka, it produced velocities of around 2400 feet per second (730 m/s) with 140 or 150 grain (9.1 or 9.7 g) projectiles. The case was two inches (51 mm) long with significant taper. Tapered cases require the use of highly curved magazines similar to that of the Kalashnikov although for the short magazines of the Pedersen and Garand rifles, this was immaterial. Both waxed and bare cartridges were made for the Pedersen and Garand rifle respectively.
At the time of its introduction, the .276 Pedersen was a solution to a significant problem. The US Army wanted a general issue autoloading rifle that would fire the .30-06 cartridge, but such a rifle was prohibitively large with existing designs such as the
Browning Automatic Rifleand French Chauchat. A weapon of the same weight as the M1903 needed to fire a smaller cartridge. Pedersen's cartridge was viewed as a compromise as it was underpowered compared to most military rifle cartridges. This decreased recoil energy made possible a reliable, lightweight semi-automatic rifle with existing technology. Despite these early problems with semi-automatic designs, Garand's design was eventually able to handle the .30-06 cartridge; the need for a lighter caliber dissolved. The Pedersen rifle was unsuitable for the .30-06 and it, too, was dropped.
World War II, British designers introduced a series of intermediate-power 7 mm cartridges for a different reason than Pedersen. They sought an answer to the Germans' highly successful 7.92 x 33 mm Kurzand various studies on the matter. The U.S. stuck with .30 caliber mostly out of a desire to have a common cartridge between rifle and machine gun combined with the perceived necessity for effectiveness out to 2000 yards. Development of a shorter .30 caliber round specifically for use in an autoloading rifle began after the war, and resulted in the 7.62x51 mm NATO, a shorter and slightly lighter round that gave nearly identical ballistics to the .30-06. Interestingly, the British studies on various cartridges culminated in the .280 Britishcartridge, which shared ballistic similarities to the .276 Pedersen in caliber, bullet weight and velocity.
Despite the failure to adopt either the .276 Pedersen or later .280 British, the concept of an intermediate power military cartridge of a 6.5 to 7 mm diameter was far from dead. Shortly after the 7.62 mm NATO cartridge was adopted,
Armalitesubmitted their AR-15 Rifleto for evaluation, the US Army suggested they redesign the gun to fire a .256 caliber projectile. Although this suggestion was fruitless, the US Army later engaged in many studies of a 6mm SAWcartridge. They, once again, sought to replace autoloading rifle and machine gun cartridges with one round. Current studies are focused on the 6.8 mm Remington SPCand 6.5 mm Grendelcommercial cartridges although their purpose is to improve on the 5.56 x 45 mm cartridge, not to develop a replacement for the 7.62 x 51 mm NATO as well.
*Hatcher's Book of the Garand. Julian S. Hatcher
*Cartridges of the World. Frank C. Barnes.
*Handloader's Manual of Cartridge Conversions. Donnelly + Townsend
*Guns. Chris McNab
*Book of Combat Arms 2005. Guns and Ammo Magazine
*Various articles in The American Rifleman. RifleShooter and Guns and Ammo magazines.
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