Optics · How-To
How to sight in a rifle scope at 100 yards
Researched by James · Updated September 26, 2026 · Editorial policy
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This process follows the published steps from Leupold's and Vortex's own sighting-in guides and the NRA's shooting series, cross-checked against the MOA/mil click math used sitewide, all linked in Sources. Full methodology & editorial policy →
Step 1: Mount the scope correctly first
A scope that isn't mounted and leveled correctly will fight you the entire time you try to zero it — you'll chase a "zero" that keeps drifting because the reticle isn't actually plumb with the rifle. If you haven't already, do this step first: how to mount and level a scope, including ring height, eye relief, and getting the reticle level.
Step 2: Bore-sight to get on paper
Bore-sighting isn't required, but it saves ammunition. On a bolt-action rifle, remove the bolt and look down the bore at a target, then look through the scope and adjust the turrets until the reticle centers on the same spot. On an AR platform, separate the upper and lower to sight down the barrel. A bore-sighting tool (laser or optical) speeds this up, but the manual method works fine. Leupold's own guidance is clear on the limit of this step: bore-sighting "is only intended to get you on target," not to replace live-fire zeroing.
Step 3: Pick your zero distance
100 yards is the standard zero distance for most centerfire hunting rifles in the U.S., and it's what most printed ballistic charts assume. Some hunters start closer, at 25 or 50 yards, to get on paper faster before moving out to confirm at 100. A few flat-shooting cartridges are zeroed at 200 yards for a flatter point-blank range, but that's a deliberate choice you make after you understand your load's trajectory, not a default.
Step 4: Fire a group and read it correctly
From a stable rest (sandbags, a lead sled, or a solid bipod on the ground — not off-hand), fire a 3-shot group at your zero distance. One shot can be a called flier; three shots tell you where the rifle is actually grouping. Measure the distance from the center of your group to your point of aim, both vertically and horizontally, in inches.
Step 5: Do the click math
Convert your measured miss into clicks using your scope's click value at that distance:
| Miss distance at 100 yd | 1/4 MOA clicks needed | 0.1 mil clicks needed |
|---|---|---|
| 0.5 in | ~2 clicks | ~1 click |
| 1 in | ~4 clicks | ~3 clicks |
| 2 in | ~8 clicks | ~6 clicks |
| 3 in | ~11-12 clicks | ~8 clicks |
This uses the standard values of 0.26 inches per 1/4 MOA click and 0.36 inches per 0.1 mil click at 100 yards. If you're shooting at a different distance, remember both units scale with range — see the full table in MOA vs MIL. Turn the turret in the direction the engraved arrow points for where you want the bullet to go: if you hit low and right, dial up and left.
Step 6: Confirm, then zero the dials
Fire another 3-shot group. If it's centered on point of aim, you're zeroed. If not, repeat the click correction — it's normal to need two rounds of adjustment. Once you're satisfied, most turrets let you reset the numbers on the dial to "0" without changing the actual point of impact, usually by loosening a set screw or popping the dial cap and re-seating it. This gives you a reliable reference to return to after dialing for wind or a longer shot.
Common mistakes that ruin a zero
- Shooting off-hand instead of a rest. You'll chase your own wobble, not the rifle's actual zero.
- Judging zero off one shot. A single round can be a called flier or a natural part of the group's spread.
- Skipping confirmation. Always fire a follow-up group after adjusting — don't assume the math worked.
- Ignoring loose rings or a loose base. No amount of clicking fixes a scope that's physically shifting under recoil.
- Zeroing hot, hunting cold. Your first hunting shot is a cold-bore shot; some rifles shift point of impact once the barrel warms.
Verdict
Bore-sight to save ammo, then do the real work at your chosen zero distance with a stable rest and real 3-shot groups. The click math is simple once you know your scope's value per click — the discipline that actually matters is shooting from a rest and confirming with a second group before you call it done.
Airgun shooters follow the same core process but usually zero much closer, since pellet and slug trajectories drop faster than centerfire bullets — see how to zero an air rifle scope for the airgun-specific distances. I run through the same bore-sight-then-confirm routine before every hunt I film; see how the rest of that setup works in my scope-cam setup and the exact load I zero for in my FX Impact M4 slug setup.
FAQ
What distance should you sight in a rifle scope at?
100 yards is the standard zero distance for most centerfire hunting rifles in the U.S., and it's what most factory ballistic charts and bullet drop tables are built around. Leupold's own guidance is to start at 50 or 100 yards, get paper contact, then fine-tune from there. Some hunters zero at 200 yards for a flatter point-blank range on flat-shooting cartridges — check your specific load's trajectory before choosing that.
Do you need to bore-sight before shooting?
It's not required, but it saves ammunition and frustration. Bore-sighting (looking down the bore on a bolt-action, or through the receiver on a disassembled AR) to roughly align the reticle with where the barrel points gets your first shots on paper instead of missing the target completely. A bore-sighting tool speeds this up but isn't necessary.
How many clicks do you move to correct a 1-inch miss at 100 yards?
With a 1/4 MOA scope, about 4 clicks, since each 1/4 MOA click moves impact roughly 0.26 inches at 100 yards. With a 1/10 mil scope, about 3 clicks, since each 0.1 mil click moves impact about 0.36 inches at 100 yards. Always adjust toward where you want the bullet to go, following the arrows engraved on the turret.
How many shots does it take to sight in a scope?
Budget at least 9-12 rounds: a few to confirm bore-sight is close, a 3-shot group to measure your correction, another 3-shot group to confirm the fix, and a final 3-shot group to verify zero holds. Fire from a stable rest every time — a rifle you can't hold steady will make you chase a zero that was never actually off.
Why is my rifle not grouping tight enough to zero confidently?
Before blaming the scope, rule out the basics: a loose scope base or rings, inconsistent cheek weld, a bipod or rest that's shifting, or a barrel that's still fouling. If groups stay open past 1.5-2 inches at 100 yards with a rest and quality ammunition, work through the accuracy troubleshooting checklist — most of it applies to firearms too.
Should you zero a rifle scope cold or after it's warmed up?
Zero it the way you'll actually hunt: cold-bore, from a cold barrel, since your first hunting shot is almost always a cold-bore shot too. Many rifles show slight point-of-impact shift between the first cold shot and later warm shots. If you only zero off a hot barrel, your real hunting zero can be off.
Do you need to re-zero every season?
Confirm zero every season and after any travel, scope removal, or hard knock to the rifle, even if you're confident nothing moved. It takes one 3-shot group and a few minutes, and it's the cheapest insurance against a clean miss on an animal.
What's the difference between bore-sighting and zeroing?
Bore-sighting only gets you close enough to hit paper; it is not a substitute for firing actual shots and adjusting turrets. Zeroing is the process of firing groups and dialing the scope until the point of impact matches the point of aim at your chosen distance. Skipping straight to hunting after only bore-sighting is a common and preventable miss.