Point of Impact Considerations 1

There are several common zeroes that a person might use for their AR15, when it wears fixed sights or a red dot. Of course, if your rifle has rear sights that are adjustable for elevation, then it's a no-brainer: use the Revised Improved Battlesight Zero (RIBZ). Similarly, if you utilize a scope with a Ballistic Drop Compensator (BDC) reticle, then zero per the manual and you are set!

For fixed sights, there are three main zeroes that most shooters use:
* Military doctrine calls for a 300 m zero. Many times, this is mistakenly called a 25 m zero. In actuality, if you wish to zero at 300, your best bet is to use a 36 yard zero. Dial in perfectly at 36, and you'll be really close at 300.
* A less common zero, but one that some folks like, is the 100 yards zero. Many ranges have a 100 yards firing line, hence the popularity.
* Possibly the most common zero is the 50/200 zero. If you dial in at 50 yards, you'll be almost dead-on again at about 200 yards. This zero offers some easy holdovers, too.

Of course, two other criteria are what length barrel you use and what round. Barrels come in several common lengths - 14.5", 16", and 20". 18" barrels produce bullet velocities that are frequently similar to 20" barrels, so no real need for the fourth option. For this discussion, we shall assume that the two most common rounds - M855 and M193 - have substantially similar trajectories under 500 yards (and they do).

100 yard zero
If you use a 16" barrel - which is quite possibly the most common AR15 barrel - here's a good dope chart for where your bullet will impact, if you are zeroed at 100 yards:

25 yards     -     1.5" low
50 yards     -     0.75" low
100 yards   -     -0-
200 yards   -     2.3" low
300 yards   -     11" low
400 yards   -     28.7" low


50 yard zero
Again, for a 16" barrel.
25 yards     -     1.1" low
50 yards     -     -0-
100 yards   -     1.45" high
200 yards   -     0.6" high
300 yards   -     6.7" low
400 yards   -     22.8" low


36 yard zero
25 yards     -     0.7" low
50 yards     -     0.8" high
100 yards   -     3.1" high
200 yards   -     3.9" high
300 yards   -     1.7" low
400 yards   -     16.1" low




Now you know your holdovers. Good luck!

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