Primary Arms

How Far Can You Shoot With A Red Dot Equipped Rifle?

An AR15 with an Aimpoint PRO red dot sight.

This article is part of a continuing partnership with Primary Arms, enjoy!

Here, we’re going to give our best thinking on how far you can stretch out a red dot sight. We think that, depending on the sight, it’s entirely possible to extend the range of these close-quarters oriented optics out to several hundred yards, if you’re willing to temper your expectations on what you consider accuracy just a little bit.

To make our case, we’re going to cover some of the things we think are important in a good red dot sight, then talk about some specific rifles and calibers that are both common hosts for red dot sights and, in our view, good candidates for trying things at longer ranges. Whether you just built a new AR 15 upper designed for long range or you just bought a new rifle, this article will cover everything.

What to Look for in a Good Red Dot?

Dot Size

When it comes to red dot sights, size matters. Here, we’re thinking in terms of golf, where lower is better. Some dots come with a 4MOA dot: that means that, in effect, that dot looks like it is four inches across at 100 yards.
A 2MOA dot, on the other hand, looks half as big. When you’re talking about shooting inside of 10 yards, it does not matter in the least, but at longer ranges, we want a smaller dot to increase our chances at a decent group.

Dot Color

Although these dots are called red dot sights in the industry, they do come in multiple colors, and it does make a difference for some people in some conditions. For most folks, red dots are fine. If your red dot sight looks like a 6MOA splotch instead of a 2MOA dot, then it’s time to look for a green sight and visit your optometrist, as you likely have astigmatism.

AR15 with a red dot sight. Photo courtesy Primary Arms

For some folks a green dot looks a lot crisper even if it is hard to see on green backgrounds, so that is what I go for when I want to press my sight out to longer ranges.

Rifle and Caliber Combinations to Try

AR15 in 5.56mm

If you’re reading this, chances are that you have an AR15 sitting in a closet or a safe nearby, and it might well have a red dot on it. If that’s you, we think that this is a good place to start in terms of trying to get more range out of your red dot, if for no other reason that it’s the equipment that you have on hand.

With that said, let’s talk about accuracy and goals for a second. The AR15 as designed by Eugene Stoner is meant as a front-line infantry rifle that privileges volume of fire over extreme accuracy. The AR, with commercial ammo and a 16” barrel, is likely a 2-4MOA gun depending on the specific sample. That means that from a bench, you’ll be shooting 4” groups at 100 yards. The goal is not to get 1” groups, the goal is to hit a man-sized target quickly and repeatably.

Given the ballistics involved, we think it’s entirely possible that, with some practice, you can make repeated hits on a silhouette target, using a red dot, out to 300 or so yards without much in terms of ammunition expended or training taken. A big caveat with this, though, is that you should zero your rifle at, say, 50 yards first and memorize the hold-overs as you go.

AR10/M1A in .308

Of course, 5.56mm has its limits: it’s a light and fast bullet that is like a laser out to about 300 yards, then starts to quickly drop off and by then it has lost a lot of its kinetic energy. This was a problem that the US military faced in Afghanistan, thus bringing the M14 back from retirement, shooting its larger .308 caliber rounds.

The best examples of either an M1A or an AR10 firing .308 or 7.62mm NATO can be1-2 MOA guns, but since these are, again, infantry rifles, expect more like 3MOA. It’s possible, with a 3MOA gun and some patience, to stretch the .308 out as far as you can see, and we think 500 yards with a red dot on a silhouette target is entirely possible assuming that the optic is well zeroed to the gun. The issue here, especially with the M1A, will be finding a good spot to mount it, and you might need to change your handguard to get some rail space.

How About a Magnifier?

One of the Primary Arms writers has his AR15 set up with a red dot and a magnifier that can swing out when not in use, and we think it’s a good setup if you only have one rifle for defensive purposes, albeit with some caveats.

AR15 with a red dot sight and magnifier. Photo courtesy Primary Arms.

The major benefit here, of course, is that you can see targets better, making it more possible to shoot at longer ranges, and our writer has gone out to 300 yards with his setup without much trouble. The issue is that it does add more weight, in this case about six ounces, to the rifle. It’s a nice convenience but might make the rifle too heavy. Also, when the magnifier is up and in the correct spot, he has to flip down his iron sights. This is not a major problem but is one more fiddly bit on the rifle that might break during a defensive situation.


To address the main question of this piece directly, we think it is possible to make effective use of a red dot sight out to 300 or more yards, depending on the rifle, the ammunition, and the shooter?
Is a red dot sight the best optic for medium to long-range engagements? Absolutely not, and we’d much rather have a variable power scope for engagements between 200 and 700 yards. With that in mind, a red dot might well be the only optic you have or can afford, on your rifle. If you have on your rifle now, we think that you should not feel totally unprepared to make long-range shots, especially if you think of the AR platform as an infantry rifle as opposed to a precision marksman’s weapon.

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