A bullet’s flight towards a target is not a straight line. Instead, gravity, air resistance, and energy loss all have an effect on its flight, creating a slight curve along the way. A hunter must always take these effects into consideration when sighting-in. A bullet sighted-in to hit a bull's eye at 100 yards might be one inch above the bull's eye at 50 yards. The hunter needs to know before practicing what type of game will be hunted and only sight-in with the ammunition that will be used in the hunt.
The key to sighting in a firearm is to reduce all the movement of both the shooter and the rifle. The hunter needs a good solid bench to sit on and a solid rest for the firearm: carpeted wooden blocks, sandbags or a tripod all work well. It is important that a hunter exercise breath control at the moment when the trigger is pulled; even the slight rise and fall of a hunter's chest when breathing can influence a bullet's trajectory.