Eotech - "The Donut of Death"
Mar 23, 2008 (Updated May 25, 2009)
Review by Trebor1415
Rated a Very Helpful Review
Pros:Quick target acquisition
Cons:Poor battery life in the N battery model. Adds weight and bulk.
The Bottom Line: A viable choice for a red dot sight
One of the great improvements in small arms technology in the last decade has been the widespread acceptance of optical sights as standard equipment on military rifles.
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The majority of the optics issued are known as "red dot" sights. These sights have a single focal plane with the red dot projected on the glass. In use the shooter looks at the sight and the red dot appears to be projected on the target showing the point of aim. Unlike a laser though, the dot is only actually in the sight and is only visible to the shooter.
There are several advantages to this over conventional iron sights. The first is that with a single focal plane the shooter no longer has to align the front and rear sights, instead he just puts the red dot on the target where he wants the bullet to go. This allows for easier, and therefore quicker, target acquisition.
Another advantage is that the sights are designed to allow the shooter to shoot with both eyes open. When the shooter focuses on the target and places the sight within his field of vision the red dot will seemingly magically appear on the target as if it was actually projected. The shooter then just pulls the trigger when the dot is on target. The standard dot scope uses a 1x magnification so there is no distortion between a non-magnified image seen with the naked eye and a magnified image seen through the scope.
The ability to shoot with both eyes open allows for greater peripheral vision. This allows the shooter to keep watch for additional threats or targets. This fact, combined with the ease of shooting with a red dot sight, makes them the premier choice for close-range shooting in what is called "CQB" or "Close Quarters Combat."
This technology was originally developed for competitive shooting, then was adapted by the military and changed to meet their requirements and now, in a full circle, those military versions are available to civilian shooters.
The two leaders in this technology are the Eotech sight made by L3 Communications and the Aimpoint sight, made by Aimpoint. I have examples of both sights. I will review the Aimpoint in a separate Epinion. This is a review of the Eotech 500 series military Holosight.
The Eotech Military Holosight uses a laser to project a Holographic reticle on a shatterproof laminate screen. This "heads up" display is the same technology used in fighter jet sights. The reticle has a 1 MOA aiming dot surrounded by a 65 MOA circle. Users often irrelevantly refer to this setup as the “donut of death”.
In use, the 1 MOA dot provides a precision point of aim while the 65 MOA circle allows for quicker, coarser, aim at CQB ranges.
The unit itself is rugged and durable. A rugged aluminum cage protects the actual optical surface. This adds durability at the price of increased weight. The controls are on the back of the sight, facing the shooter, and consist of an "UP/ON" and "DOWN" arrows. To turn the sight on, you press the "UP/ON" arrow until the reticle appears. You can then adjust the brightness of the sight as desired. To turn the sight off you press the "UP" and "DOWN" arrows at the same time.
In use the sight is parallax free and offers unlimited eye relief. You don't have to have your eye any specific distance from the scope to see the dot. The dot is visible even when your head is out of position. While the dot seems to move around on the optical laminate, the dot still indicates the correct point of aim at all times. If you can see the dot in the sight, that is where the bullet will go.
I mounted my Eotech Holosight on a Daewoo K2 semi-auto rifle using the Mil-Spec 1913 Picatinny rail and the included thumbscrew. The Daewoo rifle is comparable to the U.S. M-16A2 or civilian AR-15 rifles.
The sight is advertised to keep its zero even if it is removed and replaced on the rifle. In my experience, this is only true if you first make absolutely sure that the rifle rail and the mount are fastened down tightly and then Loc-tited in place. I did not use Loc-tite on my set up and paid the price at a defensive rifle class. After firing a few drills the mount and sight loosened up under the recoil of the 5.56 rounds. I didn't realize this until I noticed that my shots were not going where the dot was aimed and I realized I'd lost my zero. I had to quickly re-zero the rifle and spent the rest of the day tightening down the mount and sight after every relay.
Other then that user error, the sight performed well in my class. I was able to make shots much quicker at close ranges then I could with iron sights and I found that being able to keep both eyes open allowed me to have a better idea of what was going on around me. The sight does add weight and bulk to the rifle, which became more noticeable as the day went on.
My only real compliant with my unit is the battery life. I have the version that uses two "N" batteries. While this version is slightly smaller then the versions that use "AA" or "CR123" batteries, I don't think the trade-off is worth it.
I found that battery life fell well short of expectations. While the batteries lasted out the one-day class, when I went to clean the rifle the next day, I discovered they were both dead. I've since learned that the "N" battery version has a problem where the batteries will discharge even when the unit is turned off. The fix for me is to remove the batteries after every use and replace them as needed. I've also read that if you turn the unit off, remove the batteries, and then wait five minutes before replacing them, that they will no longer be drained while turned off. I have not tried this myself yet.
For this reason I highly recommend the "AA" or "CR123" version of the Holosight instead of the "N" battery version. The "AA" batteries are easier to find, but the "CR123" batteries can be shared with Surefire and similar flashlights, so the exact choice depends on your circumstances.
All in all, I found my performance at close range improved with the Eotech sight. It is rugged and easy to use and, as long you avoid the "N" batteries, is appropriate for use in competition, hunting, military and police work, or civilian self-defense.
The other popular choice for a red dot optic is the Aimpoint. I also own an Aimpoint and wrote a review of that unit as well:
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