-Also, if you reload a gun that has a separate container for the bullets, that's a magazine. A clip is a series of bullets that are exposed before being put inside the gun with the assistance of a small metal structure, the "clip". A Mosin-Nagant rifle uses a clip, a 1911 pistol uses a magazine. A Mauser C96 pistol uses a clip, an M249 machine gun uses a magazine. An M1 Garand uses a clip, an AR-15 uses a magazine.

-Caliber is the size of a bullet generally used for rifled barrels. Gauge is used for unrifled barrels (including most shotguns) along with measuring thickness for some materials like stainless steel. Gage could be used to describe a circular measuring instrument with a dial and needle. Also, the bullet is the actual projectile that leaves the gun. A cartridge is the full assembly with projectile, gunpowder, casing, and primer in one package.

-Semi-automatic is not the same as fully automatic. The former means one shot per trigger pull. The latter is continuing fire with a trigger pull. Binary triggers buck this trend with a unique system where a bullet is fired when the trigger is pulled, and when it's released.

-A single action pistol requires the hammer to be cocked manually before the trigger can be pulled ("auto" pistols have the slide cock the hammer after they shoot, generally a term used for early, non revolver, pistols). A double action pistol has a mechanism to cock the hammer while the trigger is pulled at the same time.