Zeroing means aligning your point of aim with your point of impact at a chosen distance. It is simple once you stop chasing single shots and start reading groups. Here is the whole process.
1. Mount solidly first
A zero is only as stable as the mount under it. Level the reticle, set eye relief and torque everything to spec before you fire a shot — see our scope mounting guide. A loose ring is the number-one cause of a "wandering" zero.
Before you drive to the range, check the base screws as well as the rings. A base that is loose against the receiver produces a zero that shifts in a way that looks exactly like ammunition inconsistency, and people chase it for months.
2. Boresight to get on paper
Boresighting points the bore and the reticle at roughly the same spot so your first group lands on the target rather than off the backer. Use a bore-sight tool, or on a bolt gun simply remove the bolt, rest the rifle, look through the bore at a target, then adjust the reticle to that same point without moving the rifle.
The rifle must not move while you adjust. Sandbags or a rest, and a deliberate hand on the turret rather than the rifle. If the rifle shifts between looking down the bore and turning the dial, you have achieved nothing.
On an AR or any rifle you cannot see through, a laser boresighter or a simple 25-yard first group does the same job. Start close; getting on paper is the only goal at this stage.
3. Pick your zero distance
100 yards is the standard, all-purpose zero for most centerfire rifles. A 50-yard zero is popular on carbines and works well with many LPVOs and red dots. Choose one and be consistent.
The reason a 50-yard zero suits carbines is that the bullet's path crosses the line of sight on the way up at around 50 yards and again on the way down further out, so the round stays within a few inches of your aiming point across the whole practical distance band. You can hold centre and hit, without thinking, over most of the range you will use.
A 100-yard zero is the better choice for a hunting or precision rifle where you dial or hold deliberately and want a single clean reference.
4. Fire a group, adjust off the center
Shoot a 3-to-5-round group from a stable rest. Ignore individual shots — measure to the center of the group and dial the turrets to move that center to your aiming point. Remember which unit your turrets use; if that is unclear, read MOA vs MIL first. Most turrets tell you the value per click on the cap.
This is the step people get wrong, and it is worth being emphatic: never adjust off a single shot. One round tells you almost nothing about where the rifle is shooting. Chase single shots and you will dial back and forth around the centre, burn ammunition, and finish less zeroed than you started.
For the arithmetic: if your group centre is two inches low and one inch right at 100 yards, with 1/4 MOA clicks that is roughly eight clicks up and four clicks left. Count them out and say them aloud; dialling the wrong turret is the second most common error.
Let the barrel cool between groups if it is a light sporter barrel. A hot thin barrel can walk its point of impact and you will zero to a condition you never shoot in.
5. Confirm and record
Fire a fresh group to confirm the correction held, then write down your zero and settings. Foul the barrel with a couple of shots before you trust a cold-bore zero.
Record more than the distance. Note the ammunition — bullet weight and make — because a different load will not share the zero. Note the date and rough conditions. And if your scope has a zero stop or resettable turrets, set them now so the dial reads zero at your zero. That one minute saves confusion every time you dial afterwards.
If the zero will not settle
Groups wandering with no pattern almost always means hardware, not shooting. Work through it in this order: ring and base screws, then the action screws into the stock, then the scope itself. Mounting hardware is the cause far more often than a faulty scope.
If your adjustments are not moving impact by the amount the turret promises, you may be near the end of the scope's travel. A canted 20 MOA base brings you back into the usable centre of the adjustment range.
From here, browse all rifle scopes or step up to a long-range scope once your fundamentals are dialed. Zeroing a pistol optic instead? See how to mount and zero a pistol red dot.