AR-15 zeroing.com for great instructions for bore sighting an AR15
assault rifle (and its M16A2 and M4 Carbine cousins).
Pre-sighting AR-15 sights:
- Bore sighting for zero at 50 yards should give you a relatively
flat trajectory at 200 yards. This means that the bullet
crosses your actual line-of-sight twice, once at 50 yards and again
at 200 yards with a 7 inch lift in-between.
- Bore sighing at
zero at 25 yards should give you a relatively flat trajectory at 300
yards but will be high at 100 and 200 yards.
- The US
Marines calls their procedure “Battle site Zero”, and they bore
sight for zero at 36 yards
Battle sight Zero settings (flat
trajectory at 300 meters (328 yards)
Pre-sighting the AR-15 iron sights on
the Colt Mark Target
On my Colt AR-15, the
“z” mark can be found 2 clicks above the “6/3” setting on the rear
sight elevation knob.
You must adjust your rear-sight
elevation to this setting and use the small rear sight aperture (small
With this setting, you laser sight
the Colt AR-15 rifle to 25 meters (82 yards).
This achieves a flat trajectory at 328 yards (the 300
meter battle sight zero).
Also see my notes on
Action vs. semi-automatic .223 rifles.