M1 Garand - Design Details

Design Details

The M1 rifle is a gas-operated, semi-automatic, clip-fed rifle. By modern standards, the M1's feeding system is archaic, relying on clips to feed ammunition, and is the principal source of criticism of the rifle. Officials in Army Ordnance circles demanded a fixed, non-protruding magazine for the new service rifle. At the time, it was believed that a detachable magazine on a general-issue service rifle would be easily lost by U.S. soldiers (a criticism made of British soldiers and the Lee-Enfield 50 years previously), would render the weapon too susceptible to clogging from dirt and debris (a belief that proved unfounded with the adoption of the M1 Carbine), and that a protruding magazine would complicate existing manual-of-arms drills. As a result, inventor John Garand developed an "en bloc" clip system that allowed ammunition to be inserted from above, clip included, into the fixed magazine. While this design provided the requisite flush-mount magazine, the clip system increased the rifle's weight and complexity, and made only single loading ammunition possible without a clip.

Garand's rifle was originally chambered for the .276 Pedersen cartridge, charged by means of 10-round clips. Later, it was chambered for the then-standard .30-06 Springfield. With this new cartridge, the M1 had a maximum effective range of 440 yards (400 m), with the capability of inflicting a casualty with armor-piercing ammunition well beyond 875 yards (800 m). Because of the larger diameter of the .30-06 cartridge, the modified clip held only eight rounds.

Garand's original design for the M1 used a complicated gas system involving a special muzzle extension gas trap, later dropped in favor of a simpler drilled gas port. Because most of the older rifles were retrofitted, pre-1939 gas-trap M1s are very rare today and are prized collector's items. In both systems, expanding gases from a fired cartridge are diverted into the gas cylinder. Here, the gases met a long-stroke piston attached to the operating rod. The operating rod was therefore pushed rearward by the force of this high-pressure gas. Then, the operating rod engaged a rotating bolt inside the receiver. The bolt was attached to the receiver via two locking lugs, which rotated, unlocked, and initiated the ejection of the spent cartridge and the reloading cycle when the rifle was discharged. The operating rod (and subsequently the bolt) then returned to its original position.