Misfires, Hangfires, and Squib Loads
This occurs when the trigger is pulled and the firearm does not fire. It's caused either by a weak firing pin or a defective primer that fails to ignite the powder charge.
This occurs when the trigger is pulled and the firearm is delayed in firing. It's caused by a temporary failure of the primer to ignite the powder charge.
Squib Load or "Pop Fire"
This occurs when the trigger is pulled and you hear only a slight pop and do not feel any recoil. It is usually caused by not having a powder charge in the cartridge or shotshell.
When any of these occur, keep the muzzle of the firearm pointed in a safe direction. Wait about 30 seconds, unload the firearm and take it to a gunsmith for inspection and repair.
Note: In most instances, it's not necessary to go to a gunsmith after a hangfire.