How to BZO an M-16 variant service rifle equipped with iron sights.
The M-16 is intended to be zeroed at the 36 yard line with confirmation of the zero being shot at 300 yards. The strike of the projectile or bullet will be on the same plane as your line of sight; point of aim-point of impact. (see the attached photo) And remember wind does not affect your bullet at 36 yards)
Adjustments to the sights of the rifle are done at the 36 yard line while shooting from the prone position. First fire 3 shots, center mass, onto specified BZO target. Ensuring all weapons are identified as being in a safe manner then head down range to check your shot groups. Now, triangulate the center of your first 3 shots. Apply adjustments to the sights as needed. With iron sights (and the majority of optics designed for the M-16) the strike of the bullet must be moved toward the center of the target. So, if the group is to the left, move the rear sight right. Also, be sure to mark your previous shots so it’s easier to spot fresh ones. It is important to note that if a shooters group is not within a 3 inch radius (that of a hockey puck or dip can) than no adjustments should be made; the shooter may require remediation or the rifle is broken in some way.
Now that adjustments have been made, settle into the prone at the 36 yd line and fire another 3 shots onto the specified BZO target. Once the line is cleared to move down range, check your target and follow the same procedures as before.
A 10 round confirmation should be shot at the 300 yard line. It is important to remember that wind will affect the strike of the bullet at that distance. Many shooters ruin a perfectly good BZO by making poor adjustments at the 300.
Always abide by the four weapon safety rules and ensure a combat marksmanship trainer is present to certify those who are qualifying.