The Roth–Steyr M1907, or, more accurately Roth-Krnka M.7 was a semi-automatic pistol issued to the Austro-Hungarian Kaiserliche und Koenigliche Armee cavalry during World War I. It was the first adoption of semi-automatic service pistol by the land army of a major power.
The Roth–Steyr pistol fires from an unusual style of locked breech. The bolt is very long. Its rear end is solid, except for a sleeve for the striker, but its front part is hollow and fits tightly over the barrel. The interior of the bolt has cam grooves cut into it, and the barrel has studs which fit into the grooves. When the pistol is fired, the barrel and bolt recoil together within the hollow receiver for about 0.5 inch. During this operation, the helical grooves in the muzzle bush cause the barrel to turn 90 degrees clockwise, after which it is held while the unlocked bolt continues to the rear, cocking the action as it does so. For safety with intended use by mounted cavalry, the pistol has a heavy trigger pull against the firing striker spring, similar to a hammerless revolver.
The Roth–Steyr is a locked-breech pistol, which allows the barrel and bolt to recoil together within a hollow receiver. It is chambered for a cartridge specific to this model. The Roth–Steyr does not have a detachable magazine, but features a fixed magazine loaded from the top with stripper clips. The sights are fixed, the grips are wooden and terminate in a lanyard ring. Rifling is four grooves with right-hand twist.