The Hamilton mod. 1901 was an early semi-automatic pistol of Swedish origin and was chambered for the 6.5mm Bergmann cartridge using a blowback mechanism. It is a faithful copy of the Bergmann pistol Nr 3 and its proprietary cartridges. Due to the peculiar shape of the bolt, an actuator was added to the bolt to pull it down and feed the first cartridge into the chamber. An internal hammer was retained by the trigger nose when it was retracted by the bolt during its rearward move. A strong action spring was needed in order to delay the move of the bolt and it is clear that such a move downward increased the muzzle jump.