bore sight

Noun

 * 1)  An optical device, mounted on or near the end of a firearm's barrel, used to align the sights with the bore.
 * 2)  A dummy cartridge containing a small battery-operated laser, used to align the sights.

Verb

 * 1)  To align the sights and aiming point of a firearm using a bore sight optical tool.

Usage notes

 * Bore sighting is similar to, but not as accurate as, zeroing, which normally involves adjustments made to a sight after firing at a target.