Pistol slide


The slide on the majority of fully/semi-automatic pistols is the upper part that moves with recoil during the gun's operating cycle. It serves as the bolt carrier group and partly as the receiver, and generally houses the firing pin/striker, the extractor and frequently also the barrel, and provides a mounting platform for iron and optical sights.
Through the principles of short recoil or simple blowback operations, the slide is forced back with each shot by the energy of expanding gasses caused by the combusting propellant. As it is spring-loaded, once it has moved to the rearmost position, the spring tension will push it back towards the starting position. Generally, this slide movement cycle serves three functions: the extractor will empty the chamber by pulling out the spent casing from the previous shot, the slide inertia will cock the hammer/striker to prepare for the next shot, and the bolt will push a new cartridge from the magazine into the chamber when the slide comes back forward. The cycle will be repeated for continued firing as long as ammunitions are replete, provided that there are no failure to extract/eject, failure to feed or out-of-battery malfunctions occurring.
On most modern designs, once the magazine is empty, a slide stop will catch and lock the slide at its rearmost position, and will only be released to move back forward after the slide release is depressed.
Having the slide automatically loading the chamber and cocking the hammer/striker with each prior shot is essential for the function of double-action/single-action pistols. Hammerless and striker-fired pistols, lacking external hammer that can be directly manipulated, need to have the whole slide manually pulled back to cock the hammer/striker if the gun is not already cocked for firing.