Glossary of Firearms Terms - O

O

• out-of-battery: The status of a weapon before the action has returned to the normal firing position. The term originates from artillery, referring to a gun that fires before it has been pulled back into its firing position in a gun battery. In firearms where there is an automatic loading mechanism, a condition in which a live round is at least partially in the firing chamber and capable of being fired, but is not properly secured by the usual mechanism of that particular weapon can occur.

• over-bore: Small caliber bullets being used in very large cases. It is the relationship between the volume of powder that can fit in a case and the diameter of the inside of the barrel or bore.

• obturate: Obturation is the process of a bullet expanding under pressure to fit the bore of the firearm, or a cartridge case expanding under pressure to seal the chamber. See also swage.