US Secret Weapon: The Pedersen Device
The Pedersen Device was a secret WWI weapon designed to convert the M1903 Springfield rifle into a semi-automatic firearm using a pistol-sized .30 Pedersen cartridge. While innovative, it suffered from frequent jams due to tight tolerances and a firing pin acting as an ejector. Ultimately, it was deemed impractical compared to emerging submachine guns, limiting its historical impact.









