boresight

The optical axis of a directional antenna.

A device mounted along the bore axis of a gun barrel for purposes of aligning the barrel with the gun's sights.

To use a boresight to align a gun barrel with the gun's sights.

A holiday spirit prevailed throughout the task group on these special days; stationkeeping was a bit more lax, and gun crews were off-duty so that the gunners could lubricate, adjust, and boresight their guns[…]