How to Boresight a Rifle Scope Before Your First Shot

Why boresight at all?

You just mounted a new scope. The rings are torqued, the reticle is level, and the eye relief feels right. Now you take it to the range, fire a shot at 100 yards and see nothing on the paper. Where did it go? Up, down, left, right? You have no idea, and every miss costs ammunition and patience.

Boresighting solves that. It roughly lines up the scope with the barrel before you fire, so your first live shots land on paper. It is not zeroing. It gets you close enough that zeroing becomes quick. Our mounting and zeroing guide covers the whole process, and includes a short section on boresighting. This article goes deeper on that one step: the two main methods, how to do each, and what to expect.

This is a how-to built from published references and maker information.

Two methods: visual and laser

Wikipedia's boresight article sums up the limit of every method: boresighting only gets you on paper. You still need to fire live rounds to finish the zero.

Before you start

• Unload and verify. Remove the magazine, open the action, and look and feel that the chamber is empty. Then check again. Keep all ammunition in another room or in your range bag, closed.
• Mount and level the scope first. Boresighting a scope that later moves in its rings is wasted effort.
• Secure the rifle. A gun vise, sandbags or a rest that holds the rifle still is a big help.
• Pick a distance. Many shooters boresight at 25 yards, and some at 100. Shorter is easier to see. Your target needs a clear aiming mark.
• Know your clicks. Check your scope's click value (for example, 1/4 MOA or 0.1 mil) so you can count adjustments. The site's Zero Calc tool converts offsets to clicks.

How to boresight visually

1. Remove the bolt (bolt actions) or separate the upper and remove the bolt carrier group (AR-15). Confirm again that the chamber is empty.
2. Set the rifle in a rest pointed at your target, 25 to 100 yards away.
3. Look through the bore from the breech end. Move the rifle until the target's aiming mark is centered in the circle of the bore.
4. Without moving the rifle, look through the scope. Note where the reticle sits relative to the aiming mark.
5. Adjust windage and elevation until the reticle sits on the same mark the bore is pointing at. Look through the bore again to confirm the rifle has not moved.
6. Repeat until the bore and reticle agree.

This works well on bolt guns. Wikipedia notes the main difficulty: it can be hard to see well through a long barrel. A bright target and a light background help.

How to boresight with a laser

1. Choose the right device. A chamber-type laser must match your caliber exactly. Muzzle and magnetic types fit many calibers.
2. Install it. Chamber type: place the laser cartridge in the chamber and close the action gently. Muzzle type: insert the correct arbor into the muzzle until snug. Magnetic: seat it squarely on the muzzle.
3. Turn it on and find the laser dot on your target. Indoors at a short distance is easier to see; outdoors in daylight the dot can be faint.
4. Adjust the scope until the reticle sits on the laser dot. Do not move the rifle while adjusting.
5. Remove the laser before doing anything else. Make it a rule that the boresighter comes out and goes back in its case before any ammunition comes out.

Laser boresighters to consider

Ammunition Depot lists Sightmark laser boresighters in caliber-specific and universal versions, including 7.62x39 and .22 LR models alongside these:

• Sightmark .223 Remington / 5.56 NATO boresighter for AR-15s.
• Sightmark .308 Winchester boresighter for many deer and AR-10 rifles.
• Sightmark .30-06 Springfield boresighter.
• Sightmark Universal Laser Boresighter if you own several calibers.

Optics Planet's bore sight section covers laser, magnetic and cartridge-style units from other makers. Read the instructions for your specific unit; battery type, fit and recommended distance vary.

Boresighting red dots, LPVOs and hunting scopes

Hunting scopes

Set the magnification to a middle or higher setting so you can see the aiming mark clearly, and make sure the diopter is set so the reticle is sharp. If your scope has a parallax or side-focus knob, set it to the boresighting distance so the target and reticle are both crisp.

LPVOs

Boresight at a higher power for precision, then check that the reticle is still on the mark at 1x. A properly built scope holds its point of aim through the zoom range, but it is worth a look.

Red dots

The same methods work. Center the dot on the laser spot, or on the mark you see through the bore. Many red dot adjustments are coarser than a scope's, so expect a few more clicks to cover the same distance. On an AR-15, remember that the dot sits well above the bore, so at very close range your rounds land noticeably below the dot.

Scoped rimfires

A .22 LR boresighter makes this easy, and rimfire ammunition is cheap enough that you can then refine quickly at 25 or 50 yards.

Whatever the optic, the routine is the same: boresight, remove the tool, confirm the bore is clear, then fire and adjust.

After boresighting: first live shots

1. Remove the boresighter. Confirm the bore is clear by looking through it.
2. Start close. Fire a three-shot group at 25 yards. If you boresighted well, you should be on the paper.
3. Measure the offset from your aiming point to the group center and adjust.
4. Move to your zero distance (often 100 yards for a deer rifle) and repeat until the group centers where you want it.
5. Confirm with a final group, then write down your turret settings.

Expect the first live group to be somewhat off from the boresighted point. Boresighting aligns the scope with the bore line, but bullets drop and the scope sits above the bore, so the bullet's path never matches the bore line exactly. Wikipedia notes a boresighted rifle will shoot below the boresighted spot, which is exactly why live fire finishes the job.

Use the ammunition you will actually hunt or shoot with. Ammunition Depot's .308 ammunition section and 6.5 Creedmoor section cover two of the most common scoped-rifle cartridges.

Troubleshooting

• Not on paper after boresighting: check that the scope and rings did not move, that the laser was seated fully, and that you counted clicks in the right direction. Move closer and try again.
• Turret runs out of adjustment: the mount or rings may be misaligned with the bore. Check for correct ring installation before forcing the turret to its limit.
• Laser dot moves when you rotate the boresighter: the device is not centered in the bore. Reseat it or try a different arbor.
• Groups wander: recheck ring and base torque. Our torque guide explains why it matters.

Editorial note: This is an independent editorial reference built from manufacturer specifications, retailer listings and published sources. We have not performed hands-on testing of the products discussed, and nothing here is a performance promise. Verify specifications, compatibility and the law where you live.

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