Letter: A

The act of aligning a firearm on a target.

In firearms using single projectiles at a given distance, is the measure of the dispersion of the group of projectiles fired. The optimum would be one hole no larger in diameter than a single projectile.

An estimated, or empirically determined, number of rounds that can be fired in a particular gun, of a particular caliber, before it fails to meet a particular accuracy specification. Wide variations may occur due to caliber, ammunition characteristics, firing schedules, maintenance and firearm design.

The act of subjecting a firearm and its components to special fitting and operations with the goal of optimizing accuracy.

The combination of the receiver or frame together with the other parts of the mechanism by which a firearm is loaded, fired and unloaded.

Formed or machined surfaces on the action bars which control or actuate, through cams or blocks, the movement of other parts of the firearm as the bars move in a reciprocal motion.

A member or members, which are used to connect and, thus transmit the movement of the forearm or gas system to the breech block. In many designs, the movement of the action bars controls or actuates other parts of the mechanism.

Part of the firing mechanism in certain automatic firearms, such as trigger actuator, which slides forward and back in preparing each round to be fired.

Usually taken to mean a rear sight that is adjustable for windage or elevation or both. However, adjustable front sights are sometimes used on target firearms.

Any trigger mechanism which has features that can be adjusted.