Saturday, November 13, 2010

How do I sight in my AR scope?

Had a question this week from a student who picked up a new Bushmaster AR15, threw a scope on it, and isn't sure how to sight in the scope, sometimes called zeroing. Here's the process.

What you need:
- Your gun
- 20-30 rounds of ammo
- A set of binoculars or spotting scope
- Some sand bags to rest the front of the rifle/shotgun on (or a gun rest like a Lead Sled if you have it)
- A laser bore-sighter if you can't see through the bolt (see 1 below)
- A few targets with a clear bullseye
- A range with a 25 yard and 100 yard distance

1- Bore-sight the gun. Some gun shops will do this for you when you buy a scope. In this case, skip to 2. If not, here's how you do it.

If you have a bolt that pulls out where you can see from the back of the gun down the barrel, pull the bolt out. Put the gun in a rest, look through the back of the barrel and down range at a target at 25 yards. Put the bullseye dead-center in the bore, then adjust your scope so the crosshairs of the scope are on the center. This works especially well with a bolt-action rifle, like a Remington 700. If you can't see through the back of your gun out the bore of the barrel, buy a laser bore sighting kit. They're only about $30 and let you get the barrel lined up to the scope. Pop the laser in the barrel and put the crosshairs on the laser dot at 30 yards.

Bore sighting is an important first step. It'll save you a lot of ammo and frustration so you can start hitting the paper right away.

2- Start shooting. With the gun securely rested on the bench, load a round, put the crosshairs on the bullseye at 25 yards, and slowly pull the trigger.

Here's the important trick. With the gun steady and secure, aim the crosshairs at the bullseye and adjust the scope (holding the gun very steady) so the crosshairs move from the bullseye to the hole.

Now shoot again. You should be nearly on the bullseye. If not, try again. Remember, not holding the gun steady will goof up this process something horrible.

Also, take breaks when the barrel starts to get hot. A hot barrel will shoot differently than a cold barrel, and in most cases you want the gun sighted in so it'll get the shot right when the barrel is cold.

3- Move out to 100 yards. Take a shot at 100 yards, and point crosshairs at the bullseye then adjust to the hole. Aim at the bullseye, and repeat this process until you're dialed in. That's it. Easy, eh?

A few key things to remember:
- Bore-sighting your gun first will save you a lot of time and ammo.
- Make sure you hold the gun very steady, squeeze the trigger very slowly, and take your time. Most guns shoot much more accurately than the shooter, so take your time so you don't goof the shot and blame it on the gun.
- Shoot a few rounds to confirm you're on-target.
- It's a good idea to re-zero every few months, especially if the gun was bouncing around in a case or in the safe a long time.

Good luck, and shoot safe!