Saturday, March 28, 2020


Despite it's all-time popularity, it seems many (if not most) owners do not fully understand the basics of AR-15 ballistics. I'm writing this as a reference for the many shooters whom I've trained over the past several years . . . S.L.

Let's start with the basics, just so we're all on the same sheet of music:

Sight Alignment

Sight Picture

This is the basic principle behind what we're trying to achieve.

We'll talk about techniques for firing from supported positions, breathing and trigger control later; this post is dedicating to zeroing your rifle, at 25 meters (approximately 25 yards) and 200 meters (approximately 183 meters). That's right - zeroing your rifle at 200 meters! Most people who served in the military are familiar with zeroing at 25 meters, which works pretty well given that the 5.56mm bullet will cross the line of sight at 25 meters and 300 meters. (In the old days, with the M16A1 and 55grain bullets, it was 25 and 250 meters, as shown above)

Bullet drop of M4/M855 during 25-meter zeroing

Caveat: The rifle zeroing techniques and ballistics results described within this post apply to AR- series rifles with 14.5" barrel with 1"-in-7" twists, firing 65-grain M855 ammunition.

Step 1: If your rifle is equipped with iron sights, set your sights for 25-meter zeroing (see above). At 25 meters, fire 5 rounds, aiming center mass of the zeroing target:

"5 rounds? But in the Army they taught me to zero with 3-round groups."

That's right - FIVE rounds. Reason being, you'll always have one or two "flyers", but with 5-rounds you'll always be able to find your 3-round group. The Army's cheap, they think they'll save money having soldiers zero with 3-round groups, but you spend more time chasing groups around the target. You'll zero faster using less ammo if you zero in 5-round groups.

While applying the fundamentals, aim center mass of the target and fire a 5-round shot group. Based on the location of this group, make the appropriate sight adjustments. After making the correct sight changes, fire another 5-round shot group to confirm your adjustments have aligned your rifle's sights with the center of the target, and the bullets are in the 4-centimeter circle.

"Always a few g-d flyers . . ."

It may take you more than two 5-round groups to zero, but you'll get there soon enough. This technique works whether you are zeroing iron sights, a red-dot optic system, or a scope. With a rifle zeroed to 25 meters, the round is still climbing out past 100 meters, after which the round begins to drop. Between 250 to 300 meters, the strike of the round will be the same as between 25 to 30 meters. If you were to aim center mass (with a rifle zeroed at 25 meters) and engage targets at 100 meters, 200 meters and 300 meters, your targets would look something like this:

100 meters

200 meters

300 meters

This ain't bad, so why do I need to zero out to 200 meters?

Please be aware that the above illustrations do not take into account the effects of wind on your round, and/or any failure in the fundamentals of marksmanship such as position, aim, breath control and trigger squeeze. If you are zeroed at 25 meters, the slightest deviation is magnified X10 at 250 meters . . . which brings us back to the concept I mentioned earlier: its time to zero your rifle at 200 meters.

Step 2: You're already on paper at 200, so it's just a couple clicks to bring your group down to center mass. Go ahead and zero so that your rifle is hitting point of aim at 200 meters, then confirm your zero at 300 meters - this is what I achieved the other day, at 300 meters with a red-dot optic (no scope):

The left-to-right spread is due to the wind pushing the rounds around- but look at the vertical spread: LESS THAN TWO INCHES. That's a less than two inch spread at a distance of three football fields - point of aim being center mass.

What we're talking about here is getting the most performance out of your platform. For what it's worth, the above technique can be accomplished with any sort of target, although zeroing targets with the "squares" are designed specifically for zeroing your rifle:

Happy Shooting, Folks!