Misfire

Basic Information

A stoppage of the action of a firearm caused by the failure of the ammunition to detonate when fired or (in a similar vein) the failure of an explosive charge to detonate on firing.

The main causes of misfires are:

1. Priming inert: the firing cap of a cartridge or caplock, the powder priming of an older lock type (e.g. a flintlock) or the detonator of an explosive charge has failed to function, either because it proved to be inert, has become damaged (e.g. wet priming powder) or dislodged or was not powerful enough for the task.
2. Charge inert: the propellant (in a firearm) or the explosive (otherwise) is not of sufficient quality and/or quantity to detonate.
3. Firing malfunction: the firing system, whether firing pin, lock or detonator trigger has malfunctioned and is not sending a correct signal - a firing pin may be bent, a wheelock worn so that it doesn't spark and a detonator trigger failing to generate enough current.

Typically the operator must first ensure that the system has misfired¹. The next step then depends on his system - for a repeating breech loader the most sensible response is to cycle the action, eject the misfired round and chamber another². For explosives and muzzle loaders most schools of thought recommend re-priming and trying again.

If a breech loader fails to fire after cycling the user's next response will be a visual check for miss-fed rounds or partially ejected cases. Failing that the next steps depend on the characteristics of his weapon - often he will try a different source of ammunition to ensure that he hasn't received several bad rounds and/or examine the extracted rounds to see if they are being struck. Failure to strike, or any other inability to fire ammunition known to be good will tend to imply the misfire was a type 3 and the weapon needs to be taken to a gunsmith. If cycling new ammunition in solves the problem the misfire was likely to be type 2 or 1.

For explosives and muzzle loaders, re-priming should solve a type 1 misfire, if that fails the next step is to check the firing mechanism for faults in hope of detecting a type 3. Type 2 misfires require the replacement of the whole charge, which is typically laborious and sometimes dangerous as well.

"Squibs" where the propellant fires with reduced force or "bombs" where it fires with more force than expected are also misfires, and are typically far more dangerous - a round that bombs can damage or even burst the weapon, whilst a squib can, in extremis, leave a round stuck in the barrel for the next shot to hit. Both of these can be caused by poor quality control during manufacture of either the whole cartridges or just the propellant or by aging or contamination of stored ammunition. Home made ammunition produced by inexperienced handloaders is especially prone to these sorts of misfires³. Likewise, improvised, elderly or mistreated explosives also have a tendency to misbehave. Some weapons with either poorly designed actions or low grade ammunition (let alone both) may be prone to tearing cartridge cases apart. This usually occurs during extraction - which at least means that you're not throwing propellant about - but can also mean having to take the weapon apart and fish all of the bits out⁴.

Somewhere between the misfire and the stoppage lies the "out of battery detonation" and its relatives. These are particularly exciting and occur when ammunition is triggered before the action of the weapon is in the correct position for firing - either because the weapon is poorly designed (for example allowing the firing pin to strike the primer before the breech has fully closed), because the chamber is too hot (called a "cook off") or the ammunition is over sensitive (which can be a sub case of the former). These will normally result in damage to the weapon, will often stop the action⁵ and frequently cause harm to the user, either from gas and blast from the detonation or from detached parts of the weapon flying about.

Sources

Bibliography

1. full source reference

Game and Story Use

• In the modern era, a misfire is trivial as long as the user doesn't panic and/or mistake it for an empty weapon. In previous eras it can render the firearm useless for hours. Amateur users may need to make appropriate self control checks if their weapon suddenly fails in the heat of battle.
  • "Try looking down the barrel and see if something's stuck!" (makes secret smarts roll…)
• The misfired demolition has, historically, been the source of much hilarity - going back to a partially fired charge is never all that safe, and to do so in a hurry, possibly under enemy fire, even less so - nonetheless, a good few combat engineers have been highly decorated for reviving a failed demolition on a key gate or bridge whilst under fire.
• A hang fire traditionally waits until the user is no longer holding his weapon properly (or is on his way to check the detonators) before going off.
• Out of battery detonations are extremely dangerous, and unless the character is using monkey-made weapons are best saved for worst case critical failures or curses.
• Military training often has the benefit of making the user extremely familiar with one specific type of weapon and being well drilled in responding to its various eccentricities, allowing them to resolve most minor issues without really thinking about them and to have a head start on major ones - this could be a fringe benefit of military service which would not generally be found in civilians who tend to operate their weapons under less stressful circumstances.

Footnotes

1. black powder weapons and some kinds of explosive may 'hang fire' and detonate after a delay

2. Referred to as "tap, rack, bang" by the US Forces - tap the magazine to ensure that it is seated properly, rack (cycle) the action and expect the bang as the weapon fires.

3. A common cause of 'bomb loads' (besides people deliberately overloading their rounds with propellant) is the idiot who assumes that a modern cartridge case is meant to be full of propellant. This is almost never a correct - or even remotely safe - assumption.

4. Several WW2 Italian weapons were famous for this, usually combining an unnecessarily aggressive extraction with a design that made cases tend to stick in the chamber. Prior to this, a number of late C19 rifles had an otherwise functional design undermined by cost cutting in ammunition procurement leading to copper or soft brass cases which came apart easily during extraction.

5. …but not always, and a fully automatic or driven weapon that starts firing out of battery can tear itself apart in seconds.