Rotating bolt

Rotating bolt is a method of locking the breech (or rear barrel) of a firearm closed for firing.

Ferdinand Ritter von Mannlicher, who had earlier developed a non-rotating bolt straight-pull rifle, developed the Steyr-Mannlicher M1895, a straight-pull rifle with a rotating bolt, which was issued to the Austro-Hungarian Army.

In this way it functions as a delay, ensuring that the bolt remains locked until chamber pressure has subsided to a safe level.

In some forms of delayed blowback, the rotating bolt is used as the delay mechanism: the bolt head rotates as the firing pin strikes, locking the chamber until the gas pressure reaches a safe level to extract.

As the firing pin retracts, the bolt head turns anti-clockwise unlocking the breech.