Sighting-In a Rifle

Rifle bullets don’t travel in a straight line. They travel in an arc, formed by the pull of gravity. “Sighting-in” is a process of adjusting the sights to hit a target at a specific range. Deer hunters, for example, may sight-in their rifle to hit the bull’s-eye at 100 yards. Depending on the trajectory of the bullet, this gives some variance in the game being closer or farther away than 100 yards so that the bullet still hits the vital organs without compensation or guesswork on bullet rise or drop.

All rifles should be sighted-in before every hunt using the ammunition you plan to use, especially rifles with peep or telescopic sights. Guns you sighted-in prior to your last outing could have been knocked out of alignment by a single jolt. That misalignment could mean the difference between a successful hunt and a disappointing experience.

Optional Sighting-In Techniques

Use bore or collimator sighting-in initially to line up the rifle on a paper target at 25 yards.

• Bore sighting-in with bolt-action rifles: Remove the bolt, brace the firearm on sandbags, and look directly through the bore. Correct the rifle's position until you see the bull's-eye in the center of the bore. Adjust the sights to give you a good sight picture.
• Collimator sighting-in for rifles without bolt actions: A collimator slips into the muzzle end of the barrel and allows you to adjust the sights much like bore sighting-in.

These techniques alone are not sufficient to sight-in the rifle for hunting and do not guarantee hits on your target. You must make final adjustments by firing the rifle with the same ammunition you plan to use in the field. If you do not hit the paper target at 25 yards, use a larger target or move the target closer until you can hit it to avoid wasting ammunition. Then you can adjust your sights before increasing the distance of your target.

You must sight-in your rifle with the ammunition you plan to use. Be sure you sight-in and practice firing your rifle before you go hunting.

Many hunters research ballistic charts from ammunition manufacturers and reloading companies to get information on the bullet’s rise and drop at varying distances for the ammunition they use. This allows shooters to sight-in at a specific distance. Then they can adjust their sights for the distance at which they typically shoot their game without shooting a lot of expensive ammunition or they can adjust for other distances if they cannot find firing ranges with the target distances they need.

When using sights or scopes on rifles or handguns, you see the sights and the target in a straight line. However, bullets do not travel in this same straight line. Bullets leaving the muzzle do so at a slightly upward angle, rising until their velocity becomes affected by gravity and then angling back towards the ground. This path is the bullet’s “trajectory.” At a point along the trajectory, the bullet comes to its maximum ordinate or the highest point it reaches, which is normally about 2/3 of the bullet’s distance to the target. Depending on the distance from the muzzle to the target, some bullets can rise as much as six feet or more above the line of your sight. This means that if you are shooting over a significant distance and there are obstacles like tree limbs and branches hanging down between you and your target, your bullet could hit these, never reaching your target or ricocheting off unsafely in another direction.

Other than ensuring accurate shots, sighting-in a rifle has other advantages:

• Forces you to practice
• Helps determine problems with your shooting technique
• Builds confidence in your shooting ability

Protect your ears and eyes even while sighting-in your rifle.

• Hearing protection is especially important with rifles and handguns because the muzzle blast is extremely loud and/or occurs at frequencies that can permanently damage your ears.
• Eye protection is essential with handguns to prevent damage from a burst shell, punctured primer, or lead spitting from a poorly aligned cylinder.