Hang fire is an unexpected delay between the triggering of a

firearm A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions). The first firearms originate ...

and the ignition of the

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...

. This failure was common in

firearm actions In firearms terminology, an action is the functional mechanism of a breechloader, breechloading firearm that handles (loads, locks, fires, extracts, and ejects) the ammunition cartridge (firearms), cartridges, or the method by which that mechanis ...

that relied on open primer pans, due to the poor or inconsistent quality of the powder, although modern firearms are also susceptible. The delay is usually too brief to be noticed, but can be several seconds. A hangfire should be suspected whenever a firearm fails to fire, but has not clearly malfunctioned.

Ignition sequence

The ignition train of modern firearms begins with

detonation Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...

of a small quantity of impact-sensitive

primary explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

in a primer in cartridge firearms or in a

percussion cap The percussion cap, percussion primer, or caplock, introduced in the early 1820s, is a type of single-use percussion ignition device for muzzle loader firearm locks enabling them to fire reliably in any weather condition. Its invention gave ...

muzzleloader A muzzleloader is any firearm in which the user loads the bullet, projectile and the propellant charge into the Muzzle (firearms), muzzle end of the gun (i.e., from the forward, open end of the gun's barrel). This is distinct from the modern desi ...

s. The

energy Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...

released by this detonation is intended to ignite the propellant charge of

gunpowder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, charcoal (which is mostly carbon), and potassium nitrate, potassium ni ...

smokeless powder Finnish smokeless powder Smokeless powder is a type of propellant used in firearms and artillery that produces less smoke and less fouling when fired compared to black powder. Because of their similar use, both the original black powder formula ...

. Primary explosives may deteriorate with age so they release less energy; and propellants damaged by moisture or lubricants may require more energy to ignite. These conditions may either delay the ignition sequence or cause a misfire if ignition is completely prevented. While a normal ignition sequence causes the firearm to discharge immediately when the trigger is pulled, a hang fire will be perceived as a click when the

hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nail (fastener), nails into wood, to sh ...

falls followed by the loud noise of suddenly expanding gas when the firearm discharges. The delay may be only a fraction of a

second The second (symbol: s) is a unit of time derived from the division of the day first into 24 hours, then to 60 minutes, and finally to 60 seconds each (24 × 60 × 60 = 86400). The current and formal definition in the International System of U ...

or may last for several seconds.

Procedures

A shooter may interpret the initial click of the hammer fall as an unloaded firearm or a misfire. A hang fire delay of a fraction of a second may be fast enough to correct that misinterpretation before the shooter takes inappropriate action to reload; but a longer delay may allow the shooter time to move the firearm so the muzzle points in a different (and possibly unsafe) direction, or to open the action so the cartridge is no longer confined. Unexpected discharge after the firearm has been moved from the firing position will damage whatever is in front of the muzzle, and large-caliber firearms may injure the shooter during

recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, for according to Newton's third law the force requ ...

. Unexpected discharge as the action is being opened will allow a portion of the propellant energy to burst the cartridge case and possibly damage the firearm with a risk of injury to the shooter and nearby persons. The correct procedure is to keep the firearm pointed at a safe target for thirty seconds, then remove the round. This rule is usually not followed in combat, where being without a working firearm is the bigger risk.

Legacy

The phrase "to hang fire" has come to mean a delay in progressing, for example from one task to another. entry i
Compact Oxford English Dictionary
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References

{{DEFAULTSORT:Hang Fire Firearm terminology

Ignition sequence

Procedures

Legacy

See also

References