Pedersen Device

Wednesday, March 10th, 2010

The Pedersen device is a fascinating footnote in the history of the modern assault rifle. In World War I, both sides used main battle rifles that resembled modern hunting rifles more than modern assault rifles — big, long rifles, shooting big, powerful rounds, very accurately, but very slowly. This would not do for storming enemy trenches:

John Pedersen, a long time employee of Remington Arms, was aware that the US would be entering the war at some point. Concerned about the inability for troops to effectively fire on the run while attempting to cross “No Man’s Land”, he decided to start studying the problem of semi-automatic fire that would allow them to fire from the hip without stopping. However, he also realized that there would be no way the Army would accept a totally new rifle design, as they were already struggling to produce enough Springfields, contracting to produce millions of M1917 “American Enfield” rifle with Remington and Winchester and were importing Ross rifles from Canada for training purposes.

This led him to the final design, which replaced the bolt of the standard Springfield with a device consisting of a complete firing mechanism and a small barrel for the small round. In effect, the device was essentially a complete blow-back pistol minus a receiver/grip using the short barrel of the device to fit into the longer chamber of the M1903 Springfield. The mechanism was fed by a long 40-round magazine sticking out of the rifle to the top right, and could be reloaded by inserting a new magazine. New sights were provided at the rear of the device. The system did require one modification to the rifle however, a hole had to be cut in the side of the bolt area to allow the ejection of spent rounds.

By 1917 his solution was perfected, and he traveled to Washington, DC to demonstrate it. After firing several rounds from what appeared to be an unmodified Springfield, he removed the standard bolt, inserted the device, and fired several magazines at a very high rate of fire. The evaluation team was astounded, and an immediate secret classification was applied. To deceive the enemy, the Ordnance Department decided to call it The US Automatic Pistol, Caliber .30, Model of 1918. Plans were put into place to start production of modified Springfields, which became the US Rifle, Cal. .30, Model of M1903, Mark I. Promises were made to have 500,000 ready for the 1919 Spring Offensive. The use of the Pedersen Device in the 1919 Spring offensive was to be in conjunction with the full combat introduction of the M1918 Browning Automatic Rifle (BAR).

After the war, Pederson designed a semi-auto rifle using a smaller .276 (7 mm) cartridge, but John C. Garand’s design — re-chambered for Pederson’s .276 cartridge — won the Army contract:

After the .276 Garand rifle was selected over the Pedersen rifle, General Douglas MacArthur came out against changing rifle cartridges since the .30-06 would have to be retained for machine gun use and one cartridge simplified wartime logistics. Garand reverted his design back to the standard .30-06 Springfield cartridge in 1932; the result became the M1 Garand.

The M1 Garand was the first semi-automatic rifle to be generally issued to the infantry of any nation and, in the words of Patton, “the greatest implement of battle ever devised.”


  1. [...] one 00 (“double-ought”) buck-shot round; submachine guns, which shoot pistol ammo rapidly; the Pederson device, which transforms a battle rifle into a big submachine gun; and light machine guns, which fire [...]

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