A malfunction (stoppage) is when a firearm doesn't function as intended. This can be caused by almost anything, but the most common causes are improper assembly, improper lubrication, weak springs, an overly dirty weapon, and parts breakage.

More rarely, a cartridge may explode when fired, causing what is known as a "kaboom" or "kB". This is generally due to overpressure, which has several causes: too much powder, the wrong kind of powder, bullet setback (when the bullet is seated too far into the case), and excessive heat. Kabooms (the weapon exploding) also tend to happen when a round fires out of battery.

Types of malfunctionsEdit

Malfunctions are classified by cause.


  • Failure to fire (FTFire, Type 1): Can be caused by a weak or broken hammer spring. Can also be caused by a clogged firing pin channel, especially in striker-fired firearms.
  • Failure to extract (FTExtract, Type 3): Extractor does not pull spent casing from chamber; can be caused by a weak extractor spring, worn extractor claw, or a dirty chamber.
  • Failure to eject (FTEject, Type 2): Spent casing is not completely ejected from firearm; can be caused by a weak/broken ejector spring.
  • Failure to lock (FTL)
  • Failure to chamber
  • Failure to cock: Hammer does not stay cocked back.
  • Doubling: Semi-automatic firearm firing more than one shot per trigger pull.
  • Slamfire: Firing pin may be stuck, or free-floating firing pin may have detonated the primer.


  • Failure to feed (FTFeed): Bolt or slide does not pick up next round, or picks up next round but does not feed it into the chamber. Often caused by a bad magazine spring, bent/broken feed lips, or the magazine not being inserted all the way into the firearm.


  • Failure to fire (FTFire, Type 1)
    • Failure to ignite: Primer does not detonate; primer ignites, but propellant does not burn
  • Case head separation: Caused by weakened case walls.
  • Failure to feed: In gas-operated firearms, this can be caused by the burning propellant not producing enough gas pressure to completely cycle the firearm.
  • Failure to extract (FTExtract, Type 3): Can be caused by dirty ammunition.
  • Slamfire: Can be caused by a soft primer.
  • Squib load: caused by a insufficient powder load, leading to a round stopping in the barrel. If the squib is not removed and another round is fired it will cause a catastrophic failure.