Envision this: It’s 1917, at the height of World War One. Over a million U.S. soldiers are stationed in France, many of them armed with the workhorse battle rifle, the M1903 Springfield. The fighting is fierce and bloody, with both sides of the conflict taking heavy casualties daily. Then one day, a firearms designer steps forward with something that could drastically tip the scales in America’s favor: a quick-to-install device capable of turning those old hunk-o-timber bolt-action battle rifles with a five-round capacity into a fearsome semi-automatic with a 40-round magazine. That invention was known as The Pedersen Device.

Where you’ve seen it:

Not on screen. At best, behind glass at a museum. If you come across one of these in your granny’s attic, treat it with care—the last one that went to auction at Rock Island Auctions fetched nearly $50,000. Though 65,000 were built, almost all of them were destroyed following the war.


As is often the case during wartime, when presented with a better means of kicking your enemy’s ass, you tend to pay attention. A high-capacity, autoloading pistol-caliber rifle would be a significant advantage in the close proximity of the European trenches, and the U.S. War Department knew it. John Pedersen, a savant arms designer John Browning once called “the greatest gun designer in the world,” brought forth his idea for the rifle conversion, rattling through a couple sample magazines before the brass in a top secret demonstration. As they picked their jaws off the floor, the powers that be broke out their pens and ordered 100,000 Pedersen Devices to be fulfilled by Remington Arms. They planned to catch the Germans off guard with the new weapon in the Spring of 1919. Fortunately, the war ended shortly after production began. The device never saw frontline use, as it was later decided that a new standard rifle was the order of the day—not a retrofit like the Pedersen Device.


Automatic Pistol, Caliber .30, Model 1918, Mark I
The Pedersen Device came with a handy dandy scabbard to hold the conversion bolt when not in use. The Pedersen Device, magazines, and ammo would have added 14 extra pounds to an infantryman’s kit.

The Pedersen Device is essentially a conversion bolt that utilized the existing trigger mechanism and stock of the M1903 Springfield to convert the rifle to semi-automatic—firing a 30 caliber pistol round via a simple blowback mechanism. The rounds were loaded from a 40-round external magazine that protruded from the rifle at a 45-degree angle (above).

The cartridge: