In double-action revolvers, each time the trigger is pulled, the weapon fires and the cylinder advances to the next round. Single-action revolvers require that the hammer be manually cocked before each shot. A revolver's cylinder usually holds six cartridges. Pistols - A pistol carries its extra cartridges in an ammunition magazine usually located in the handle of the handgun. Each time the weapon is fired, a new cartridge is loaded into the chamber.
Junk guns are disproportionately the weapon used in homicides and other crimes.
Caliber - The caliber of ammunition refers to the diameter of the bullet. Bullets of larger caliber create larger wounds and cause more damage. A bullet, its propellant charge, and igniting primer charge are joined as a single unit known as a cartridge or round.