The Pedersen Device M1918
Case 28

Springfield Armory NHS, US NPS

AUTOMATIC PISTOL, CALIBER .30 MODEL OF 1918 - During World War I Mr. J.D. Pedersen designed a device which, inserted into the receiver of a modified Model 1903 rifle, gave the rifle the capability of firing 40 pistol sized .30 caliber bullets in semi-automatic mode. Secrecy surrounding the development of this 'Pedersen Device' resulted in it being called an automatic pistol.

M1903 Mk.I without Pedersen Device SPAR6292

M1903 Mk.I with Pedersen Device SPAR1324


close-up of left side showing ejection port
The Pedersen Device was made to fit a slightly modified Springfield M1903. The most apparent modification consisted of an ejection port cut into the left side of the receiver, as can be seen in the weapon above. This modified rifle was designated the Mark I.

Springfield Armory NHS, US NPS

view of M1903 MkI showing magazine in M1918 Automatic Pistol
The Pedersen device replaced the bolt in a modified Springfield 1903 and enabled the weapon to fire pistol-type cartridges from a forty-round magazine.

Springfield Armory NHS, US NPS

The Pedersen Device kit
When the device was not in use it was carried on the soldier’s belt in a special scabbard.

The device took up so much space in the rifle’s receiver that a full-size rifle cartridge could not be fired. Special pistol-size rounds were developed for use.

Five forty-round magazines were carried in pouches hung from the infantryman’s belt.

Special tools, carried in their own pouch, were needed to complete the field installation of the Pederson device into the Springfield 1903.

Springfield Armory NHS, US NPS

Last updated: February 26, 2015

Contact the Park

Mailing Address:

Springfield Armory National Historic Site
One Armory Square
Suite 2

Springfield, MA 01105


(413) 734-8551

Contact Us