Malfunctions range from temporary and relatively safe situations, such as a casing that did not eject, to potentially dangerous occurrences that may permanently damage the gun and cause injury or death.
Following gun safety rules can prevent firearm malfunctions, and limit the damage inflicted by them if they do occur.
[citation needed] A dud (also a misfire or failure to fire) occurs when the trigger is pulled but the primer or powder in the cartridge malfunctions, causing the firearm not to discharge.
The bullet from a squib stuck in the barrel must never be cleared by subsequently attempting to fire a live or blank round in the weapon.
A possible reason could be because of the firing pin spring of a gun being too stiff to not release the sufficient power to strike the primer and ignite the gunpowder.
This malfunction is not to be mistaken with a squib load which the gunpowder is ignited and the bullet fires, but is trapped in the barrel of a gun.
Failure to feed is common when the shooter does not hold the firearm firmly (known as limp wristing), when the slide is not fully cycled by the preceding round, or due to problems with the magazine.
A slamfire is a premature, unintended discharge of a firearm that occurs as a round is being loaded into the chamber, when the bolt "slams" forward (hence the name), as a result of the firing pin having not been retracted into the bolt, or from the firing pin being carried forward by the momentum of returning to battery.
A stovepipe or smokestack can occur in bolt-action, pump-action, lever-action, semi-automatic, and fully automatic firearms that fire from a closed bolt, when an empty cartridge case gets caught partway out of the ejection port instead of being thrown clear.
A double feed occurs when two rounds are picked up from the magazine and both are moved to be fed into the chamber at the same time.
When the firearm is out-of-battery, the round is not fully chambered, or the bolt face is not against the rear of the cartridge, and if the round is fired in this situation, the case will fail, causing high-pressure hot gases, bits of burning propellant, and fragments of the casing itself to be thrown at high speed from the firearm.
Some malfunctions with cartridges can be attributed to poor quality or damaged ammunition (often due to improper storage, exposure to moisture).