AR Rifle Optics , Even the Best Optics Can Fail the Task

Harsh, challenging and realistic conditions can beat even the best of AR Rifle Optics.

H&K MR762A1 Rifle with Trijicon ACOG 6X48mm Reticle
H&K MR762A1 Rifle with Trijicon ACOG 6X48mm Reticle
Defense Training International, Inc
Defense Training International, Inc

Ft Collins, CO –-( High-magnification optics on ARs:

During an ARTA Course (Armed Response to a Terrorist Attack) on the East Coast last weekend, a student brought an H&K MR762A1 Rifle (commercial version of H&K’s 417), with a 6x ACOG optic (6×48) mounted on the upper receiver.

This is an gas-piston, autoloading, military rifle in 7.62×51 (308), with an “AR profile”

Like all ACOG optics, the 6×48 is rugged and thoroughly militarized. But it is bulky, heavy, and pricey ($2,500.00). Reticle is a glowing, orange triangle, with assorted other aiming points, designed around the 308 round. Reticle illumination is self-powered, so the optic does not require batteries.

I’m sure the combination of rifle and optic would turn-in a suburb performance at 300m-600m, but we were shooting in heavy brush, in the rain, in low light, at targets from twenty to thirty meters.

Targets were steel silhouettes, ensconced within fall foliage. My student could not find the targets in his scope!

Trijicon ACOG 6X48mm Reticle
Trijicon ACOG 6X48mm Reticle

He cast about for long seconds, alternately squinting and moving his head back and forth, trying with scant success, to determine where targets were.

When he tried to illuminate targets with a high-powered flashlight, it only made matters worse! Flickering glint from glistening foliage made the task of locating targets in the brush through the ACOG all but impossible!

To be sure, the task was challenging for Aimpoints and EOTechs too, not to mention the best iron sights, but the rest of my students (so equipped) were still able to do it with significant success.

The second day, my student removed 6×48 ACOG from his rifle, and ran with iron sights.

He did slightly better. At least he could find targets!

High-magnification optics are convenient for making-out down-range detail. As Jeff Cooper put it, they don’t improve your shooting, but but they do enable you to see better than would be possible through iron sights or zero-magnification red-dots!

Through high-magnification optics, your get to see “a lot of a little.” For that privilege, you inherit considerable bulk and weight. Plus, all such optics are eye-relief-critical, and thus must be mounted so that they are just a few centimeters in front of your sighting eye.

Bottom line is that the rifle and optic combination described above, wonderful though it was, proved itself unsuitable to the close, rapid, 100-meters-and-closer, low-light-in-the-cold-rain, shooting that we did.

Red-dots did much better. And, for those with young eyes, iron sights run just fine also, be they Western-style or Soviet-style.

The lesson learned by all present was:

  1. You have to run your gear, and yourself, under realistic, even harsh, circumstances, before you can be sure it will serve you adequately.
  2. No one piece of gear, no matter the configuration, does everything well. You give-up some capabilities to get others.
  3. When you can’t predict the challenge, high-specialized gear is usually contraindicated!

“It all looks great in the showroom” ~ Anon


About John Farnam & Defense Training International, Inc
As a defensive weapons and tactics instructor John Farnam will urge you, based on your own beliefs, to make up your mind in advance as to what you would do when faced with an imminent and unlawful lethal threat. You should, of course, also decide what preparations you should make in advance, if any. Defense Training International wants to make sure that their students fully understand the physical, legal, psychological, and societal consequences of their actions or inactions.

It is our duty to make you aware of certain unpleasant physical realities intrinsic to the Planet Earth. Mr Farnam is happy to be your counselor and advisor. Visit:

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Jim in Conroe

I would agree that in a tactical rifle, you don’t need all that power in a scope, if your shooting in the 20 to 100 yard range. I have an older Leupold CQ/T Mark IV 1×3 that works quite well, and is usually on 1. But this is also true on hunting rifles. I have Leupold 3×9’s on two of mine. Out to 100 yards, I dial it back to between 4 and 5; at 200 yards, I use 9 to observe the target, but dial it back to 7 or 8 to make the shot. The main advantage to… Read more »

Mike Hughes

There are classes taught for the ACOG that teach the shooter to use the scope occluded at ranges under 100 yards. The Marine Corps teaches this method. Essentially, you block the objective lens and shoot with both eyes open. The “open” eye sees the target and the “blocked” eye superimposes the dot over the target. It takes a little practice, but it works.

Kevin P McCarthy

Iron sights will work every time out to 800 yards all day long. You just have to put the time behind them. Scopes… Well … They can’t make a poor marksmen an expert. Too many things can go real bad with any scope. Mounts, optics, tracking or climate.We Kick the hell out of a lot of optic shooter in across the course in service rifle category. Garbage in…. Garbage out!

Jim Macklin

The advantage of the optical sight is the single aiming point, no sight alignment is required. When I was shooting .22 gallery at 50 feet I used a 15X Lyman Supertarget Spot scope with a Lee dot that just covered the 1/8 inch and fit inside the X ring on the gallery target. It wasn’t fast but it was accurate on a 40XB Remington. The exit pupil was about 1 mm and the objective lens was adjustable for parallax down to 20 feet as I recall. It would be totally wrong for an AR unless you were just testing 100… Read more »


Over powered optics can be a real problem. Whether you are in a tactical or hunting situation. A proper fitting rifle and properly mounted optics and a lots of practice mounting your long gun and finding targets are the keys to reducing problems. As a Law enforcement instructor and firearms trainer I conducted and ran many dozens of courses as mentioned in the article. During few such training section there were students running 3×9 scopes on top of there rifles. going through the different course set ups several times. Using the optics on 3x they decide to see if there… Read more »


The student had a 6x optic, not a 20x target scope? I would venture to say that it wasn’t the 6x power of the optic that was a problem, it was that the rifle probably didn’t fit the student very well. Gun fit – which is emphasized in shotguns – is often overlooked in rifles. I have a Leupold 6×42 with heavy crosshairs on my .375 H&H and it has worked SUPERBLY for me on all my hunting trips, including a couple of African safaris where I took Cape buffalo and other game in some thick “simbiti” brush; it’s a… Read more »