A squib fire may refer to a squib load or a hang fire, both of which are extremely dangerous. Severe injuries result from firing subsequent rounds using a weapon with a barrel blocked by a squib load or round. The squib load causes structural failure of the weapon.
A squib round occurs when a weapon is fired but there is insufficient force for the ammunition to exit the barrel. Such rounds may result from a variety of causes including improper loading or defective powder or cartridges. The extreme pressure resulting from firing subsequent rounds causes the barrel to weaken or split and releases an explosive force in the hand of the user.
A hang fire is a result of an unexpected delay between the time a weapon is fired and the ammunition actually exiting the barrel. The user may inadvertently point the weapon at an unintended target or himself to investigate the problem or try to dislodge the round, only to have it discharge at that point.