Accidental discharge is the event of a firearm discharging (firing) at a time not intended by the user. Perhaps most commonly, accidental discharges (sometimes called ADs by military and police personnel and referred to as negligent discharges by several armies) occur when the trigger of the firearm is deliberately pulled for a purpose other than shooting—dry-fire practice, demonstration, or function testing—but ammunition is mistakenly left in the chamber. Unintentionally leaving a firearm loaded is more likely to occur when the individual handling the gun is poorly trained, and perhaps also with removable-magazine-fed firearms (as the magazine may be removed, giving an unloaded appearance even when a round remains chambered—see discussion of magazine-safeties below).