How to Zero a Scope at 100 Yards — Step-by-Step Guide

Zeroing your scope at 100 yards is one of the most important skills a shooter can master. Whether you’re a hunter dialing in your bolt-action, a competitive shooter prepping for a match, or an AR owner wanting reliable first-shot confidence, a proper 100-yard zero gives you a consistent reference point for holdovers, ballistic charts, and wind calls. This guide walks you through everything: the gear you need, step-by-step zeroing, turret math, troubleshooting common issues, and advanced tips to carry that zero out in the field.

Why zero at 100 yards?

A 100-yard zero is a familiar standard because it makes math simple, is practical for many hunting scenarios, and gives predictable ballistic references for mid-range shooting. From a ballistic perspective, 100 yards often places many hunting cartridges near their peak or on a predictable trajectory, allowing easier holdover estimates for typical shots. It’s also an excellent baseline: once your scope is truly zeroed at 100 yards, you can build ballistic tables for 200, 300 yards and beyond.

Gear checklist (what you’ll need)

• Rifle with a mounted scope (rings properly torqued)
• Stable rest (bipod, sandbags, or shooting bags)
• Solid shooting bench or rest (bench rest preferred)
• Paper target with clear aiming point (1″ grid or bullseye)
• Bore sighter or laser bore sight (optional but speeds the process)
• Quality ammunition (use the exact load you plan to shoot)
• Wind meter (optional)
• Ear and eye protection
• Cleaning kit (if needed)
• Notebook and pen (record adjustments / conditions)
• Tools for turret adjustments (coin, flat screwdriver if needed)

Safety first range rules to follow

1. Always treat the rifle as loaded until verified.
2. Keep the muzzle pointed downrange at all times.
3. Wear eye and ear protection.
4. Confirm the range is clear before firing.
5. Follow local range commands and regulations.

Step-by-step: Zeroing a scope at 100 yards

1. Prepare the rifle

• Ensure the action is clean and the barrel free of obstructions.
• Confirm scope mounts and rings are tight and torqued to manufacturer specs. Loose mounts = inconsistent zero.
• Use the exact ammunition you intend to hunt or shoot with — different loads often have different points of impact (POI).

2. Initial bore-sighting (optional but recommended)

• Use a bore-sighter or remove the bolt (for bolt-actions) and visually bore-sight to align the barrel with the target. This gets your first shots on paper and saves time and ammo.
• If you don’t have a bore-sighter, start at a very close distance (e.g., 25 yards) to get on paper and then move back.

3. Set up the target at exactly 100 yards

• Measure the distance accurately — 100 yards = 300 feet. Use a reliable rangefinder or measured range.
• Mount the target on a sturdy target stand and ensure your aiming point is clearly visible.

4. Stabilize your rifle

• Use a bench rest, bipod, and rear sandbag to minimize human error. A consistent, repeatable position matters more than raw skill when zeroing.

5. Fire a three-shot group (or five) for best results

• Aim at the exact center of the target and fire a 3-shot group (or 5 if you want more data). Let the barrel cool between groups if you’re doing multiple strings.
• Record the group center relative to the bullseye.

6. Measure the error (windage and elevation)

• Measure how far (in inches) and in what direction your group center is from point of aim (POA). For example: 2.0″ high and 1.5″ left.

7. Convert inches to MOA and then to turret clicks

• Important math refresher: At 100 yards, 1 MOA ≈ 1.047 inches, commonly rounded to 1 inch for easy field math.
• If your turret adjusts 0.25 MOA per click:
  • Error of 2.0″ high → ≈2 MOA high → 8 clicks down (2 ÷ 0.25 = 8).
  • Error of 1.5″ left → ≈1.5 MOA left → 6 clicks right (1.5 ÷ 0.25 = 6).
• Always move the turret in the direction you want the bullet strike to travel on the target (most modern scopes mark turret directions: “UP” lowers POI on the target).

8. Make the adjustments

• Dial the turret the number of clicks calculated. If your scope has a zero stop or resettable turret, use the provided method to track your zero. If turrets are finger-tight, use the tool provided.

9. Confirm with another 3-shot group

• Fire another group from the same rest and measure again. If the group center is within 0.5″ of POA, you’re essentially zeroed for most hunting purposes. For precision work, continue refining until you’re satisfied.

10. Final verification — and test different positions

• Try a final 5-shot group and test from a field rest (bipod prone or kneeling) if you’ll be shooting from those positions in real life. Confirm POI consistency.

Turret math cheat sheet

• 1 MOA ≈ 1.047″ @ 100 yards (approx 1″ for practical field use)
• If turret = 1/4 MOA per click: 1 MOA = 4 clicks → 1″ = ~4 clicks
• Example: To move 3 inches at 100 yards on a 1/4 MOA turret: 3 ÷ 1 ≈ 3 MOA → 3 × 4 = 12 clicks

Common zeroing mistakes (and how to avoid them)

• Using different ammo for zeroing than in the field: Don’t do it. Different bullet weight/velocity shifts POI.
• Loose scope rings: Always torque rings to spec. Loose rings = shifting zero.
• Not stabilizing the rifle: Human error inflates group size — use rests for repeatability.
• Not accounting for wind: Even small breezes can push groups at 100 yards — pick a calm day or use a wind flag.
• Wrong math direction: Double-check turret directions — turning the wrong way wastes time and ammo.
• Inconsistent cheek weld and trigger technique: Your position must be consistent between shots.

Ammo selection & consistency

Zero with the exact brand, bullet weight, and lot of ammo you intend to use. If you plan to use match loads for competition and hunting loads for the field, zero both and note the POI difference. Often hunting rounds shift POI slightly from match loads — record these offsets so you can quickly adjust in the field.

Boresight vs. live-fire: pros and cons

• Bore-sighter: Fast, cheap, gets you on paper. Not a substitute for live-fire confirmation.
• Live-fire: Required. Only live groups show real POI accounting for barrel harmonics, ammunition variation, and human factors.

Using ballistic reticles and BDC (bullet drop compensator)

Some scopes have BDC reticles or holdover marks calibrated for a specific cartridge and velocity. Once zeroed at 100 yards, you can use the reticle to hold for known distances, but you must confirm that the BDC lines match your chosen ammo and muzzle velocity. It’s best practice to verify holdovers with live fire before relying on them in the field.

Advanced tips — beyond the basic zero

• Zero at the temperature and atmospheric conditions you’ll be shooting in (if extreme conditions are expected). Temperature and altitude affect velocity and point of impact.
• Use a chronograph if you need precise ballistic tables — velocity variance directly impacts drop.
• Record the zero: note rifle, scope, ring height, ammunition, date, range, and conditions in a logbook. This helps reproduce the zero later.
• Check zero after any change: aftermarket stocks, retorquing rings, cleaning barrels (sometimes POI shifts after initial cleaning), or transport.
• Consider 2-point zeroing: some shooters zero at 100 yards then confirm at 200 to match preferred ballistic trajectory for their cartridge.

Quick field adjustments and tricks

• If you need a fast field-adjustment and you’re off by a few inches, convert inches to clicks using the turret math cheat sheet and adjust.
• For tactical or AR platforms: confirm that the upper/lower receiver interface hasn’t shifted and that the rail mount is stable.
• If your scope doesn’t have finger-adjustable turrets, carry the correct tool and mark your zero position on the turret with a permanent marker or tape.

Example zeroing log (sample entry)

Rifle: Remington 700
Scope: 3–9×40, 0.25 MOA clicks
Ammo: 168gr HPBT, Federal Match (lot #1234)
Date: Oct 8, 2025
Range: 100 yards, calm (2–3 mph)
Group 1: 3 shots, 2.5″ high, 1.0″ right → Adjustment: 2.5 MOA down (10 clicks), 1.0 MOA left (4 clicks)
Group 2: 5 shots, 0.2″ low, 0.1″ left → Zero confirmed

Troubleshooting stubborn zero issues

• Group high/low inconsistency: recheck head position, cheek weld, and trigger pull.
• Shots stringing vertically: might indicate inconsistent ammo, gas system issues (on semi-autos), or shooter anticipation.
• Large groups off POA dramatically: suspect loose rings, loose base, or barrel problem. Re-torque mounts, reseat rings, and recheck.

FAQ — Fast answers

Q: Is 100 yards the “best” zero?
A: It’s a standard, great baseline for many cartridges and makes MOA math simple. Depending on your rifle and hunting needs, some prefer 50/200 or 200-yard zeros for flatter trajectories at typical hunting ranges.

Q: How many shots should I fire for a reliable zero?
A: At least a 3-shot group for initial checks; 5-shot groups are better for confirmation.

Q: Do I need a bore sighter?
A: No, but it speeds the process and reduces wasted ammo. Always confirm with live fire.

Q: Do turret clicks really equal 0.25 MOA?
A: They should — verify by moving the turret a known number of clicks and measuring actual change on target.

Conclusion

Zeroing a scope at 100 yards is a repeatable, logical process that brings consistency and confidence to your shooting. With the right gear, a steady rest, careful measurement, and the turret math above, you’ll be able to establish a reliable zero in minimal time. Record your settings, test different shooting positions, and always verify after any gear change. Practice the steps until they become muscle memory then your first shot at game or on the line will be a calm, predictable result.

If you’d like, I can create a printable 100-yard zero checklist, a turret-click calculator sheet, or a printable target sized for your preferred aiming point tell me which and I’ll generate it for you.