3 definitions by J.R., PhD, MD, PsyD, Esq.

(verb) the act of decocking a handgun with an exposed hammer by pulling the trigger while the thumb of one's firing hand rests on the hammer, stopping the hammer's motion, then slowly allowing it to move until it rests at the base of its travel without striking the firing pin with sufficient force to ignite the primer of a chambered round.
I was afraid Jeb was going to put a hole through the floor of my car when he cowboy decocked his revolver.
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(verb) to go through the motions necessary to discharge a firearm or ranged weapon, but without any functional projectile loaded into its chamber
It can be damaging to a bow to dry fire it.
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(noun) a dummy round, typically used while training with a firearm to avoid potential damage to a firing pin. Often has a spring-loaded dummy primer in the case of center-fire guns.
If you don't have a snap cap for your .22, you can use a yellow drywall anchor.
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