An unintentional discharge is the event of a firearm discharging (firing) at a time not intended by the user. An unintended discharge may be produced by an incompatibility between firearm design and usage, such as the phenomenon of

cooking off Cooking off (or thermally induced firing) is unfired weapon ammunition exploding prematurely due to heat in the surrounding environment. The term is used both for detonation of ammunition not loaded into a weapon, and unintended firing of a load ...

a round in a closed bolt machine gun, a mechanical malfunction as in the case of

slamfire A slamfire is a discharge of a firearm occurring as a cartridge is being loaded into the chamber. Some firearms are designed to slamfire, but the term also describes a malfunction of self-loading firearms. Shooters accustomed to firearms requir ...

in an automatic weapon, or be user induced due to training issues or negligence. The phenomenon has also been defined in scientific literature as ''an activation of the trigger mechanism that results in an unplanned discharge that is outside of the firearm’s prescribed use''. Where prescribed use refers to departmental policies and laws related to the operation of firearms (O'Neill, 2018).

Types

Accidental discharge

An accidental discharge (AD) occurs when there is a mechanical failure of the firearm. This can include things like firearms that do not have mechanisms to render them drop safe falling a sufficient distance, a firing pin stuck forward, a sear failing, or rounds heating sufficiently to spontaneously ignite in the chamber (as may happen in a closed bolt machine gun).

Negligent discharge

A negligent discharge (ND) is a discharge of a firearm involving culpable carelessness. In judicial and military technical terms, a negligent discharge is a chargeable offence. A number of

armed force A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...

s automatically consider any accidental discharge to be negligent discharge, under the assumption that a trained soldier has control of his firearm at all times. This is the case in the

United States Army The United States Army (USA) is the land warfare, land military branch, service branch of the United St