Zero Your AR: Irons, Red Dots & LPVOs

Prep the rifle, target line, and notes

Repeatable zeros start with a controlled setup. Treat zeroing like an inspection event, not casual plinking.

• • Verify an empty chamber, insert a chamber flag, and pack the magazines you plan to use for duty.
• • Mount the rifle in a stable rest or supported prone position; bag the stock and handguard to remove muscle tremors.
• • Hang fresh zero targets with known reference grids at 25, 36, 50, or 100 yards depending on your plan.
• • Record atmospheric notes (temperature, ammo type) for future comparisons.
• • Stage a torque driver, sight tool, and paint pen so you can lock down hardware after the final group.

Best Zero Distance: 36/300 vs 50/200 vs 100 Yards

AR-15 optic height (~2.6" over bore) means your projectile climbs to meet line of sight, crosses it, rises, then drops back through it. Choosing a plan tells you where those intersections happen so holds stay simple.

No matter which curve you choose, record it in your log book and zero card. That way holds for head/low-probability targets become instinctive instead of guesswork.

Zeroing backup iron sights

Start with irons even if you run an optic. They confirm the bore-to-rail relationship and give you a fallback sighting system.

1. 1. Mechanical zero: center rear windage, set front sight flush, and note the baseline clicks.
2. 2. Choose a zero distance. 50/200 yards keeps close holds simple, while a 36/300 yard zero matches legacy military BDCs.
3. 3. Fire a three- to five-round group from prone or bench, focusing on consistent sight picture.
4. 4. Adjust front sight for elevation (clockwise lowers point of impact) and rear sight for windage.
5. 5. Fire another group to confirm; repeat until groups center on the point of aim. Record final click values and apply witness marks.

If impacts string vertically, check your front sight for wobble or loose gas block screws before burning more ammo. Heat shifts usually mean hardware movement, not bad fundamentals.

Purchasing through these links may generate a commission at no extra cost to you. Always confirm torque specs and follow your department or range safety zeroing policies.

Step-by-Step Red Dot Zeroing Process

Mechanical offsetMechanical Offset[Optics]The vertical distance between the center of the bore and the center of the optic (approx. 2.6 inches on AR-15s). You must aim high at close ranges to compensate. is the only magic trick with red dots. Build a process that accounts for the bore being ~2.6 inches below the optic.

• • Use a laser boresight or co-witness irons to get on paper before you start live fire.
• • Confirm mount torque, then fire at 36 or 50 yards. These zeros give a second intersection near 200 yards, minimizing high/low holds.
• • Dial adjustments in the optic's stated increments (0.5 or 1 MOA per click are common).
• • After centering, step back to 10 yards and verify your close hold-under (impact should be roughly 2.6 inches below point of aim).
• • Finish with a five-round confirmation group at 100 yards to prove the zero scales beyond CQB distances.

Keep zero cards taped inside your dust cover or stock—list the distance, ammo, and date so troubleshooting later is easy.

LPVO and magnified optic zero

Magnified optics demand more time on leveling and parallaxParallax[Optics]An optical illusion where the reticle appears to move relative to the target when your eye moves. Most optics are set to be parallax-free at a specific distance (e.g., 100 yards).. Get those right and dialing turrets becomes a data entry exercise.

1. 1. Confirm the scope is leveled to the rifle using levels or a plumb line before you step to the line.
2. 2. Dial the parallax/focus knob until the reticle is crisp and parallax is minimized at your zero distance.
3. 3. Fire slow three-round groups at 100 yards (or your reticle's recommended distance) from a fully supported position.
4. 4. Use the turret scale to dial corrections; convert inches to MOA/MRAD (1 MOA ≈ 1.047" at 100 yards).
5. 5. Repeat until two consecutive groups land centered. Reset turrets to zero/lock if your optic supports it.

After zeroing, confirm holds at 300–400 yards using reduced steel or paper. Dial or hold according to your BDC, and document the results so you trust the data later.