To adjust the sights of some projectile weapon, especially a firearm, in order to achieve an accurate shot. The verb can be used transitively or intransitively. These scopes have a wide range of adjustment options, so sighting them in is extremely easy and precise. Remember to sight in before you start hunting with the new rifle.
See also: sight
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.