How Do I Zero a Red Dot Sight on My AR-15?

Why It Matters

An improperly zeroed optic means you will miss your target. A red dot must be zeroed to a specific distance so you know exactly where your bullet will impact relative to the dot at any range. The 50/200 zero is the most popular because it keeps the bullet close to the point of aim across the widest range of practical engagement distances without any holdover adjustments.

The Detail

Step-by-step zero procedure:

1. Preparation:
- Bore sight first if possible (saves ammunition)
- Use a stable shooting rest, bipod, or sandbags — eliminate human error
- Shoot from prone or bench rest position
- Use consistent ammunition (same brand, weight, and lot number)
- Let the barrel cool between groups

2. Initial zero at 25 yards (to get on paper):
- Set up a large target at 25 yards
- Fire a 3-round group, aiming at center
- Note where the group hits relative to your aim point
- Adjust the red dot: move the dot toward where you want the bullet to go
- Most red dots adjust in 1 MOA clicks (1 click = 0.25 inches at 25 yards)
- Fire another 3-round group to confirm adjustment

3. Move to 50 yards for final zero:
- Set up a fresh target at 50 yards
- Fire a 5-round group at center
- Adjust until the group is centered on the point of aim
- 1 MOA click = 0.5 inches at 50 yards
- Confirm with two more 5-round groups

Common zero distances and their characteristics:

50/200 yard zero (most recommended):
- Zero at 50 yards, bullet returns to zero at approximately 200 yards
- Maximum trajectory height: +1.5 inches at 100 yards
- At 300 yards: approximately -8 inches (aim slightly high)
- Best for: general purpose, home defense, patrol

36-yard zero (true 100-yard zero):
- Zero at 36 yards, bullet impacts point of aim at exactly 100 yards
- Maximum trajectory height: +1.0 inches at 75 yards
- At 200 yards: approximately -4 inches
- Best for: range shooting, known-distance targets

25-yard zero:
- Quick and easy, common military zero
- Bullet crosses line of sight at 25 yards and again at approximately 300 yards
- Maximum height: approximately +3.5 inches at 150 yards
- Drawback: significant holdover needed at 100 to 250 yards

Adjustment direction:
- If bullets hit LEFT, move the dot RIGHT (or windage turret as marked)
- If bullets hit LOW, move the dot UP (or elevation turret as marked)
- Always follow the arrows or labels on your specific optic — they indicate impact direction

Build Impact

After zeroing, apply a witness mark on your turrets with a paint pen or nail polish so you can visually confirm the zero has not been bumped. Torque your mount to specification and re-zero if you ever remove and remount the optic. Keep a zero confirmation target in your range bag — shoot a 5-round group at 50 yards at the start of every range session to confirm zero before training.