First appearing at the end of the 19th century, self-loading pistols have been produced in almost every conceivable caliber and size and in several materials. Such guns have also been designed in most recognized operating systems, all being a function of expanding gas.

These operating systems include short recoil, long recoil, simple blowback, retarded blowback and delayed blowback. Confused? Let’s take a closer look at these operating systems.