Final answer:
The mechanism that uses recoil energy from the firing of a round of ammunition to operate the weapon's mechanism, extract the fired case, eject it against spring tension, and return the mechanism to firing position again is called a recoil-operated mechanism.
Step-by-step explanation:
The mechanism that uses recoil energy from the firing of a round of ammunition to operate the weapon's mechanism, extract the fired case, eject it against spring tension, and return the mechanism to firing position again is called a recoil-operated mechanism.
When a round of ammunition is fired from a firearm, the force of the expanding gases pushes the bullet forward, but it also generates a reactive force that pushes the firearm backwards. This backward force, known as recoil, is utilized by the recoil-operated mechanism to cycle the weapon's action.
One example of a recoil-operated firearm is the semi-automatic pistol. As the round is fired, the slide of the pistol moves backward, extracting the fired case, ejecting it, and compressing the recoil spring. When the slide returns forward under spring tension, it chambers a new round and prepares the firearm for the next shot.