The verdict first: torque the mounting screws to the manufacturer's specification, level the reticle to the rifle, bore sight at 25 yards, then shoot three-round groups at 100 and move the group to the point of aim. Nine rounds is a normal zeroing session. Two boxes means something is wrong with the rifle, the mount or the process — not with your shooting.
This page is the scoped-rifle procedure. If your rifle wears a red dot the distances and the failure modes are different and there is a separate walkthrough: how to zero a red dot.
Step 1: mount it properly, because this is where zeros die
A rifle that will not hold zero has almost always been assembled by feel. Manufacturers publish inch-pound figures for base screws and ring caps for a reason, and the two failure modes sit either side of that number: too loose and the base walks under recoil, too tight and you deform the scope tube.
- Degrease the screw threads and the receiver holes.
- Torque base screws first, in a cross pattern, to the figure the base manufacturer publishes.
- Set the scope in the rings, then bring the ring caps down evenly — a few inch-pounds at a time, alternating corners, until they reach specification.
- Leave an even gap on both sides of each ring cap. An uneven gap means uneven clamping.
Step 2: level the reticle to the rifle
A canted reticle produces an error that is invisible at 100 yards and enormous at 800, because the error grows with the amount you dial. You cannot correct it later by dialing — you have to fix it at the bench.
Level the rifle first, using the flat of the rail or the action, then level the scope's turret cap or elevation housing to the same reference. Two magnetic levels do this in about ten minutes.
Step 3: get on paper at 25 yards
A laser bore sighter or, on a bolt gun, simply removing the bolt and looking through the bore, gets you close enough that the first shot lands on a large target at 25 yards. Fire one round, and move the group to the point of aim.
25 yards is not the zero. It is a mechanical convenience for finding the paper cheaply. Do not stop here, and do not rely on the "25-yard equals 100-yard zero" folklore — it is trajectory-specific and it is wrong more often than it is right.
Step 4: the actual zero, at 100
Move to 100 yards, off front and rear bags or a bipod and rear bag, and fire a three-round group. Measure from the center of the group to the center of the bullseye — not from your best shot, and not from your worst.
Convert that measurement to clicks. This is the one place a calibrated target earns its money: a grid printed in clicks means you read the correction off the paper instead of doing arithmetic on a windy bench. If you are converting inches to angular units yourself, the rulers are explained in full on MOA vs MRAD.
Dial the correction, fire a confirming three-round group, and if it is centered, you are done. Reset the turrets to zero per your scope's instructions and write the date and the ammunition in your log.
Step 5: confirm, then leave it alone
Fire a cold-bore shot on a subsequent day before you trust the zero for hunting. The first shot from a cold, clean-ish barrel is the shot that matters in the field, and it is not always in the middle of the group you shot warm.
What you actually need to buy
The short list
- A torque wrench, or a gunsmith who owns one.
- A levelling kit, if you intend to shoot past 300 yards.
- A calibrated target in the unit your turrets adjust in.
- Front and rear support, or a bipod and a rear bag.
That is the whole list. Everything else in this category is optional, and one popular item is genuinely not needed by most people — see the skip pick above.
Match the target to the turret
A target gridded in quarter-MOA clicks is useless in front of a MIL scope, and vice versa. Mixing rulers is the classic and expensive mistake in this whole subject, which is exactly why we keep pointing at the MOA versus MRAD page rather than re-explaining it here.
Ammunition consistency beats everything
A zero belongs to a rifle and a load. Change the ammunition and you have changed the zero, sometimes by a lot. If you hunt with one load, zero with that load, and do not confirm with cheap practice ammunition.
If you handload, the equipment side of that is on why I handload for long range — and note that nothing on this site publishes load data.
Three-shot groups, not five, and not one
One shot tells you nothing about where the rifle shoots. Five costs ammunition and heats the barrel. Three is the working compromise for zeroing, and the group center is the datum — a zero adjusted off a single flyer is a zero you will chase all season.
