Pistol slide

Source: Wikipedia, the free encyclopedia.
A SIG Sauer P226 with slide closed (top) and opened (bottom). On the bottom view, slide is locked to the rear by the slide stop.

The slide on the majority of fully/semi-automatic pistols is the upper part that reciprocates ("slides") with recoil during the gun's operating cycle. It serves as the bolt carrier group (BCG) 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

cartridge from the magazine into the chamber when the slide comes back forward. This action cycle will be repeated for continued firing as long as the magazine contains rounds and there is no failure to extract/eject (which causes stovepiping and double-feeding), failure to feed, or out-of-battery malfunction
.

Fully/semi-automatic

shots
have no casings that needed to be extracted (unlike firearm cartridges), a very brief slide movement is sufficient to cycle the action and load the subsequent shot, so only a small amount of energy is needed to move the slide.

On most modern designs, once 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

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.

See also