Have you been at the range and just can‘t seem to hit that bullseye? You might need to re-zero your scope, but you also might think it's too hard. Thankfully it is a lot easier to do than you may think. Here's an easy way to do it yourself—it's quick and practically foolproof. (If you've already sighted in your rifle and just want to check your gun's zero, skip to the section labeled "Verifying Zero.")
Bore sighting roughly aligns the scope to the barrel and reduces the number of required shots to zero your scope and get you on paper faster. You can do this with a bore-sighting tool you insert in the muzzle of your gun or by shooting a few shots that will serve as a reference point for the adjustment.
The second method can only be done with a bolt-action, AR-15 or other gun where you can look down the bore of the rifle. A range of 25 yards is highly recommended when using either bore-sighting method.
First, secure the gun in a cradle and remove the gun's bolt so you can see the bore. Line up your barrel on a spot 25 yards away. Then adjust your scope so it's sighted in on that same spot. Make sure the rifle doesn't move and be sure to recheck the alignment. When using a bore-sighting tool the process is much the same except you won’t remove the bolt from the gun and will adjust the scope to align with the tool.
You should start at 25 yards for the best chance to land your shots on the target paper. Pick a steady bench and use sandbags or a shooting rest to support your rifle. Looking through your scope, aim at the center of a target, and shoot two shots at one spot on the target. Measure the distance from where you thought you were shooting (point of aim) to the center of the group of shots (point of impact).
Adjust your scope so the point of aim is moved to the center of the group. Shoot two more shots and you should find your point of impact is very close to your point of aim. To sight in for other distances, repeat the same procedure at that distance.