The Pedersen Device for M1903

Pedersen designed a device to caliber convert a Springfield M1903 from a 5 round bolt action rifle into a semi auto 40 rd 30cal rifle.

Jerry Miculek took a look at one at the Institute of Military Technology.


Ian McCollum of Forgotten Weapons has a video of a M1903 shooting the Pedersen Device.

Nicholas C

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  • Anonymoose

    It’s not a caliber conversion. It’s a cartridge conversion.

    • Matthew Brennan

      Any info on cartridge? weight, velocity, etc..

      never mind… 80 grain projectile, 1300 fps, 3.5 grains of bullseye

      • Ken

        Yeah, the French actually adopted it as the 7.65 Longue for their Mle 1935 pistols.

  • John

    semi auto only?

    eta: semi only. He said it in the second video.

  • Don Ward

    I’m a fan of the Pedersen device as it was an innovative way to give added firepower to troops in the peculiar tactical environment of WW1. I’ve debated this with Nathaniel but I’ve always considered these to be a precursor to what we know as the “assault rifle” giving troops with one weapon system the ability to fight at both long and close range (rifle and pistol rounds), possessing at least semiautomatic ability, an extended magazine and produced in sufficient quantities to arm entire divisions and corps of men,

    I’m not sure how it would hold up in the mud of the Western Front, and it was a finicky procedure to remove the standard rifle bolt, slide in the Pedersen device, load it and fire it. But still, innovative for the day.

  • Juice

    I’ve been waiting for Ian’s video on the Pederson ever since he first mentioned that it was coming up. Miculek’s video was nice but I was really disappointed that they didn’t show the action operation of the device. Good to see that Ian’s quality video covers this!

  • Ken

    Wait, how are they NFA items? They should be no more NFA items than a .22 CMMG conversion bolt.

    • Patrick Mingle

      I believe he said submachine gun in the first video but Ian clearly states and shows semi-auto in the second. Maybe there were two different versions? The production numbers also vary quite a bit so I would assume there was a semi-auto and a full-auto version

      • Ken

        As far as I know, they were all semi auto.

      • Tassiebush

        In the forgotten weapons article on it Ian points out in comments section that the triggers and sears were modified to go with the device then afterwards many were refurbished back so I wonder if the difference is that it was designed as a semi auto system and would be so if matched with correct trigger group but if you pop it into the wrong rifle that’s been refurbished the simpler trigger group without a disconnector will make it operate as a full auto? Just speculation on my part though.

  • Joe

    When I was at the Knights museum, It was Cory that was the tour guide. Great museum and a great guide, however It kinda sucked that the ONE gun that I wanted to see up close was kept in a non access room we could only look into.

  • gunslinger

    video states it was complex mechanical design. that means $$$ to “redesign” then $$$ to manufacture.

    • BryanS

      Your second $$$ was missing a $$.