Here is how to sight in at 25 yards for 100 yard zero. It's very simple and most people can go to their local indoor shooting and or outdoor range to get it done.
Before anything, get some good quality zeroing targets here if you don't have any. These are useful for people who don't have access to a 100-yard range.
- Zero for 25 yd first
- Reference bullet drop offset between 25 and 100
- Add turret offsets for 25 yard zero for 100 yard
- Verify zero
Setup Zeroing Target At 25 Yards
Staple an good quality zeroing target you can see well at 25 yards.
Remember the distance to 25 yards measures from the tip of the barrel, and we highly recommend using an affordable laser rangefinder to measure the distance instead of eyeballing it for the best accuracy.
Know Your Ballistics
Different bullet has different ballistic performance at different distances, please use this ballistics calculator to find out how much the bullet drops at 100 yards and 25 yards while using different barrel length.
The purpose of doing this is so you can zero the rifle with a bullet drop offset at 25 yards.
Collect 3 Shot Group
- Find a target point and send 3 rounds down range with proper breathing and slow trigger squeeze. No need to rush it.
- Zero for 25 yard first to set the reference point
Rest your rifle on a steady platform, and we highly recommend the BOG Deathgrip tripod to stabilize your aim. It works even better for the outdoor range if you don't want to go prone on the muddy ground.
In addition, make sure the rifle's barrel isn't exerting tension on a sling or other objects to interrupt the barrel harmonics.
Note: If you're zeroing a red dot sight, it's always helpful to use a magnifier scope to zoom in the sight picture to get a finer aim.
Adjust Optic Turrets
Measure how much you missed for both elevation and windage.
Follow this equation to calculate the MOA click adjustments:
Number of clicks to turn = [Missed distance / 0.25] / turret click value
Remember: The direction of the turret reference the point of impact
If the reticle moves in opposite direction of the adjustment, you may have referenced the point of aim.
Once zeroed at 25 yard, now it's time to adjust the turret offset for the bullet drop. We can do this by referencing a bullet drop chart. Please check out https://www.federalpremium.com/ballistics-calculator
This example shows -2.5 MOA drop at 25 yard for 55gr 5.56 NATO round, so this means at a 25 yard range, your point of impact should be about 2.5 MOA below the point of aim.
Assuming using a 0.5 MOA / click optic.
The number of clicks to adjust 2.5 MOA for elevation is: 2.5 / 0.5 = 5 clicks DOWN
Once you've adjusted the turret, now verify the shot group to see if the point of impact is as close to the point of aim.
If not, make some finer adjustments to get close.
When you have time, be sure to verify at an actual 100 yards range to see the difference. Because an actual 100 yard range will have wind affecting the bullet performance.
Once completed, mark the turret to note where the turret is zeroed, so any misaligned mark can tell you the optic is off.