Snap cap left|thumb|An assortment of snap caps of varying calibers A snap cap is a device that is shaped like a standard cartridge but contains no primer, propellant, or projectile. It is used to ensure that dry firing firearms of certain designs does not cause damage. A small number of rimfire and centerfire firearms of older design should not be test-fired with the chamber empty, as this can lead to weakening or breakage of the firing pin and increased wear to other components in those firearms. In the instance of a rimfire weapon of primitive design, dry firing can also cause deformation of the chamber edge. For this reason, some shooters use a snap cap in an attempt to cushion the weapon's firing pin as it moves forward. Some snap caps contain a spring-dampened fake primer, or one made of plastic, or none at all; the springs or plastic absorb force from the firing pin, allowing the user to safely test the function of the firearm action without damaging its components.
Snap cap left|thumb|An assortment of snap caps of varying calibers A snap cap ,is a device that is shaped like a standard cartridge but contains no primer, propellant or projectile. It is used to ensure that dry firing firearms of certain designs does not cause damage. A small number of rimfire and cent.erfire firearms of older design should not be test-fired with the chamber empty, as this can lead to weakening or breakage of the firing pin and increased wear to other components in those firearms. In the instance of a rimfire weapon of primitive design dry firing can also cause deformation of the chamber edge. For this reason, some shooters use a snap ,cap in an attempt to cushion the weapon's firing pin as it moves forward. Some snap caps contain a spring-dampened fake primer, or one made of plastic, or none at all; the springs or plastic absorb force from the firing pin, allowing the user to safely test the function of the firearm action without damaging its components