How to Zero Your Rifle Scope

If you buy a scope for your rifle, change scope mounts, adjust the position of your current scope, change the barrel, or change your typical ammunition, you need to zero or re-zero your rifle and scope. This article will review the basics for getting your rifle zeroed so you can get out and shoot accurately, whether for hunting or target shooting.

First, let’s talk about what zeroing your scope means, and then we’ll go over a simple process to get your bullets hitting where you want. (If you want more info on the best long range scopes, check out our article.)

Simply put, zeroing your scope (or "zeroing your rifle") means making the aim of your scope match the point of impact of your bullets at a certain distance.

Most American hunters and centerfire rifle shooters zero their scoped rifles at 100 yards, though some may choose 50 or 200 yards or another distance. We will use 100 yards in our example below because: 1. This is a commonly measured distance offered at American shooting ranges; 2. It’s fairly easy to estimate; 3. It’s not too far to walk to check your groups; 4. Many ballistic-ranging reticles assume a baseline zero of 100 yards; and 5. It corresponds nicely to MOA (minute of angle) adjustments on sight-in targets, and many American-built scopes are calibrated in MOA. (See below for more on that.) If you’re zeroing a .22LR rifle, consider a 25 or 50-yard zeroing distance.

First, your scope must be installed correctly and perfectly level

Before you even think about zeroing your scope, you must ensure it’s installed properly and is perfectly level, the rings/screws are torqued correctly, and the scope and rifle “fit you” in your desired shooting position.

• We won’t go into the process of mounting a scope here, nor bedding, shimming, or lapping your scope rings. If you choose to do this, awesome. We’re assuming you use straight/quality rings that won’t damage your scope when tightened correctly.
• Consider using a torque-calibrated screwdriver like the Wheeler FAT wrench to tighten your scope ring screws to your manufacturer’s specifications.
• Adjust your scope and/or mounts forward or rearward so you have a clear view through the scope in the shooting position you plan to use and at the magnification setting you use the most. If you shoot primarily from prone, adjust your scope’s position while lying prone. Many people will adjust and install their scope while standing offhand or from a bench, and the scope will be too close to their eye (or too far) when in the prone position, for example.
• The scope reticle must perfectly align with the vertical/horizontal planes and gravity. The easiest way to do this is to hang a plumb bob line and align the vertical crosshair of your scope exactly with the line. You can also use bubble levels on your rifle’s receiver (if possible) and the scope. Usually, the top surface of the turret will be level with the reticles, but you shouldn’t assume so. Check with a plumb line if you can.
• Ideally, your scope or rifle should have a bubble level mounted so you can confirm vertical/horizontal alignment before each shot.

Important note: Even if you can't get your scope rail/rings/mount perfectly level with the receiver, or the receiver level with true vertical, as long as the RETICLE of the scope is level/plumb with the vertical and horizontal, your accuracy will effectively be as good as you can get it for your setup. In a perfect world, both the receiver of the rifle and the scope reticle will be perfectly level with each other and with a true vertical/plumb line.

But even if your rifle has no flat surfaces on the receiver anywhere (like many older hunting rifles and military bolt-actions), as long as your rifle’s reticle is perfectly level with true horizontal/vertical, accuracy will be minimally impacted within reasonable distances. The bore can be offset or canted compared to the center/level of the scope, but as long as the scope itself is mounted level in the mount, accuracy will be minimally impacted by any bore/mount/receiver cant.

An extreme example is the M1D sniper rifle or the mounted WWII anti-tank rifles with scopes offset to the left of the receivers. As long as the scope is level with the horizon/plumb-vertical, they are acceptably accurate for most hunting and informal range shooting at normal distances.

So: If you have to choose between 1. A level scope and a slightly canted rifle; and 2. A level rifle and a slightly canted scope; choose the level scope every time.

Zeroing your rifle: start at 25 yards, and visually bore sight your scope if possible

To avoid wasting lots of time and expensive ammunition (and potentially sending unsafe shots beyond your backstop), it’s a good idea to begin your zeroing process at 25 yards. It doesn’t have to be exactly 25 yards, but somewhere in that range is good. Set up a target with a prominent feature you can see with your naked eye, such as a large colored block or bullseye.

Ideally, you’re now going to visually bore sight your scope to your rifle before you take any shots. (Laser boresighters are available and are fine to use if you have one, but they are unnecessary.) Get in a stable shooting position (the one you plan to shoot from when it counts). If prone, use a shooting bag or bipod with a rear bag for support, at your preference. Whatever you use, the rifle must be absolutely stable.

For bolt actions, you can remove the bolt and then get your eye behind the receiver and look through the barrel at a conspicuous point on the target that you can discern through the bore. For AR-platform rifles, you can remove the rear pin, hinge the action open, remove the bolt carrier group, and stabilize the rifle to see through the bore. On many ARs, you can remove the front pin and use the upper for bore-sighting.

Treat the barrel as two circles: A dark circle at the rear of the barrel and the light circle of the muzzle opening. Make sure the two circles are aligned center-to-center with each other, similarly to using a peep sight, then center a recognizable portion of the target in the bore opening as you look through it. Make sure the rifle is absolutely steady, then lift your eye to the scope and see where the reticle is aligned on the target.

As you go back and forth between the scope and the bore, you can see any misalignment, then remove your turret caps or unlock them and adjust the scope’s crosshairs so they line up with the object or target feature you have centered in the bore. Check this several times.

Note: Since you’re moving the actual reticle/crosshairs to align with your bore’s center or theoretical point of impact, you’re actually going to turn them in the opposite direction from the "up" or "down" positions marked on your turrets. Those directions describe the way you want to move the bullet’s impact when making adjustments after zeroing, not the direction you’re moving your actual reticles. To move the actual reticle down (if that’s the direction you need to go to align with your bore-sighted object), you turn the turret in the "UP" marked direction. If this sounds confusing, hold the rifle super steady and twist the elevation turret while watching which way it moves, and adjust based on which way you need it to go to align the crosshairs with your bore-sighted object.

Once you’re confident that your view through the bore and the scope’s reticle is aligned sufficiently well on your 25-yard target, You’re ready to take a shot (after donning eye and ear protection). If you’ve done this initial zero correctly, your shot at 25 yards will be fairly close to your bore-sighted target object or feature. If it’s WAY off, check your process again and maybe fire another shot, but the goal here isn’t to fine-tune your zero at 25 yards (unless you want a 25-yard zero) but rather to get you close enough at 25 that you’ll be hitting the target paper at 100, where you’ll make your final adjustments. Due to scope-to-bore offset, a well-zeroed rifle’s impact will actually hit an inch or two low at 25 yards, so if your first shot is somewhere around there, that’s fine.

Zeroing at 100 yards: shoot a group, then adjust your elevation and windage turrets

After you’re fairly close at 25 yards, it’s time to finish the process by shooting at a target at 100 yards, ideally with a 1-MOA/1-inch grid pattern (or .1 mils/MRAD if you prefer). Adjust the eyepiece and parallax adjustment (if any) so the target and the reticle are perfectly focused. Always dry fire a few times before shooting any ammunition, and be honest with yourself. If you don’t see perfect sight alignment or your breath or trigger control is shaky, keep dry firing until you get a few “shots” off without any issues. Then you can shoot your first zeroing group.

Always shoot at least a 3-shot group before adjusting your scope, and 5-shot groups are better. If you shoot one shot and then adjust your turrets, you’ll likely be chasing your impacts all over the target. A 3-shot group is a minimum to get a consistent idea of where your bullets are actually hitting.

After you fire your first group, examine your target. Chances are, the center of your group will not be perfectly aligned with where your reticle was aimed. Now is the time to make the fine adjustments to elevation and windage to move the point of impact to align with your point of aim. Now, since you’re moving the point of impact to align with where your crosshairs are aimed, you turn the adjustment dials/turrets in the "correct" or marked direction; i.e., if your group is low and to the right, you’re going to turn your turrets in the "up" and "left" directions to move your point of impact.

A brief discussion of MOA (minute of angle) vs. MRAD (milliradians, or mils)

If you’re more of an "eyeball it" kind of shooter, you can certainly twist your turrets "a bit" in the direction you think is needed and shoot another group, then adjust. Still, to save time and money, it’s best to know how your scope is calibrated and what units of measure it’s built to conform to. The two main options for long-range scopes are known as MOA (minutes of angle) and MRAD (milliradians, commonly called "mils"). Similarly to how a minute is one 60th of an hour, a minute is one 60th of a degree. At 100 yards, each minute of each degree of a 360-degree circle around the perimeter of the shooter’s position measures 1.047 inches, or close enough that we can effectively equate one MOA with one inch at 100 yards. That’s easy for most Americans to understand and allows for more precise adjustments at closer ranges than MRAD scopes.

An MRAD, or "milliradian," is a bit more complicated for most Americans to understand. Still, it’s an easier system for making large wind calls at long distances since one MRAD is about 3.6 inches at 100 yards, and typically, each click of an MRAD scope moves the point of impact further than on an MOA scope. An MRAD is calculated by dividing the circumference of a circle into 6.28 equal sections that measure 57.3 degrees each (or the length of one "radian" around the circumference). This gives us a circle that has a circumference of 6.28 radians. If each radian is divided into 1,000 milliradians, then we find that there are 6,280 milliradians in a circle.

A zeroing target with 1-MOA/1-inch squares is very useful, but you can also measure with a ruler and calculate your adjustments. If your scope has ½ MOA clicks and your group is 4 inches to the left and 2 inches high at 100 yards, you need to come to the right 8 clicks and down 4 clicks, then fire another group. If your scope has ¼ MOA clicks, double those clicks for the same adjustment.

If your scope is in mils, with adjustments/clicks in .1 MRAD increments, and your group is 7” high and 3.5” to the right at 100 yards, you need to come down approximately 2 mils, or 20 clicks and left approximately one mil, or 10 clicks, then shoot another group, and adjust if needed.

If you have an MRAD scope and favor zeroing at 100 meters (109.3 yards), a single mil equals 10 centimeters. That means that a single click of a 0.1 mil scope adjustment turret will move the impact by 1 centimeter at 100 meters.

If you do your measurements correctly and shoot good, steady groups, you can be effectively zeroed after about 5-6 shots fired (one at 25 yards, and a 5-shot group at 100, then adjust correctly). We recommend shooting at least one more 5-shot group after you reach your desired zero to confirm. We also highly recommend confirming your zero by shooting a group before each hunt or each match.

After your scope is zeroed, cap your turrets or loosen and “baseline” them

Older hunting scopes may not have provision for “slipping the scales” or adjusting the elevation and windage turrets so that their “zero” positions line up with the external markings on the scope, and that’s fine. Just cap your turrets so they don’t get bumped out of adjustment, and go hunt!

Suppose your scope has lockable/adjustable turret caps. In that case, you can follow your manual and loosen the caps/adjustment turrets so they spin freely (without making any clicks or adjustments to the crosshairs), turn them back to the “zero” baseline positions, and re-lock them. If you need to make further adjustments for a particular shot, you can always find your way back to your scope’s zeroed position.

How to perform a scope tracking test

Tracking refers to how accurately your scope mechanically "tracks" your turret adjustments and your point of impact. A basic “box” tracking test is easy: shoot a group at 100 yards, on the lower left area of a large paper target, with vertical/horizontal index lines or crosshatches at 1-inch intervals. Dial 3 mils (or 11 MOA, depending on your scope) elevation, and fire another group using the same aiming point as your original group. Then dial 3 mils (or 11 MOA) right windage, and shoot another group (using your original aiming point). Then dial 3 mils/11 MOA down, and shoot your final group, using your original aiming point.

(Note: 3 mils or 11 MOA is an arbitrary number that keeps the "box" size reasonable for most large paper targets. It doesn’t matter how much elevation and windage you dial for your particular test as long as it’s consistent each time and your target is large enough to capture all your groups. Generally, the larger your dialed adjustments, the more informative the box tracking test will be.)

If all goes well, your groups should mark the corners of a perfect square, consistently aligned with the elevation and windage you dialed. If your groups are not where they should be, you may have a scope that’s not tracking properly, or there may be an issue with your rifle or scope mounts that needs to be checked.

Another way to test scope tracking that’s very useful for long-range shooting (as well as verifying that your bubble level and scope are level, which is crucial) is the "tall target" test. Here’s an excellent video detailing how the tall target scope tracking test works, including calibrating any correction factor.