By Mike Searson
The EOTech is similar to a red dot sight in principle but works on a completely different theory. The technology behind the EOTech comes from Synthetic Aptitude Radar (SAR) as used on modern fighter jets for weapon systems.
A laser is used to generate and project the EOTech’s reticle into the user’s focal plane by means of a hologram that displays within the prism of the glass on the sight.
EOTech developed this concept in the early 1990s for the military and licensed Bushnell to produce a commercial variant a few years later known as the Holosight to test the waters with the civilian shooting public.
After a sound proof of concept through Bushnell by thousands of hunters, competitive shooters and law enforcement agencies, EO Tech rolled out a Milspec version that was more robust with better lenses and a protective outer shell that wraps around the top of the unit to protect the glass.
Additionally they disposed of the Weaver style mounting system of the Bushnell in favor of the Picatinny rail mount that was quickly becoming the tactical standard.
Key benefits conferred by the EO Tech include:
- The ability of the shooter to keep both eyes open and preserve peripheral vision.
- Unlimited eye relief, allowing its use on handguns as well as long guns.
- Rapid target and sight picture acquisition.
- Parallax free at any distance, angle or direction.
- The use of inexpensive AAA batteries instead of lithium batteries.
- Accurate out to 300 yards.
- Night vision compatibility with some models
Another benefit not often discussed is that since the reticle projects onto the glass, the sight is still functional even if the lens is shattered, and more than one veteran of Iraq and Afghanistan has returned home with working EOTechs even though the glass in them was shattered by gunfire.
Single battery EOTechs have a battery life of close to 600 hours and the two-battery versions can double this run time.
Our model is the 512, and we have run it on everything from rimfire carbines to rifles and machine guns chambered in 5.56 NATO and 7.62 NATO.
The EOTech can mount directly to a Picatinny rail which is by far the new standard in scope mounting. However we decided to use a LaRue Tactical QD mount that allows us with the flip of the switch to move this sight around more efficiently by means of a throw lever.
Pull the handle straight back, give it a turn and you can go from an AR15 to an AR10 to a Tavor or even a Ruger 10/22 if you so desire. The point of impact will shift going from one platform to another, but this mount greatly eases the installation process.
In close to a decade of use, we have had no problem with our EOTech, apart from its short battery life when compared to other sights. However, other problems have been discovered in a way that will have far reaching implications for EOTech and perhaps the outdoor industry as a whole.
In November of 2015, EOTech was sued by the US Government for mistake of fact and unjust enrichment, arising from a scheme to defraud the United States Department of Defense (“DOD”), the Department of Homeland Security (“DHS”) and the Federal Bureau of Investigation. The government held that EOTech knew their combat optical sights were materially defective and that design defects in the sights caused them to fail in cold temperatures and in humid environments. EOTech was contractually obligated to disclose these defects to the DOD, so that the DOD could prevent defective products from being fielded to troops.
EOTech represented to DOD that its sights performed in temperatures ranging from -40 degrees to 140 degrees Fahrenheit and in humid conditions. EOTech claimed that they tested the sights in accordance with military standards to ensure that they met the advertised specifications while knowing that they failed to perform as represented in temperature extremes.
The sights experienced a condition referred to as “thermal drift,” meaning that the sight’s point of aim differed from its point of impact (or “failed to hold zero”) when subjected to hot or cold temperature and waited nearly a decade to disclose the defect. In March of 2015, the FBI independently discovered the thermal drift defect and presented EOTech with the very same findings that the company had documented internally for years but withheld from DOD.
A separate issue was discovered in 2007 regarding failure in cold temperature. When temperatures dropped to freezing, the reticle became distorted, affecting accuracy and degrading as the temperature dropped to -40 degrees. At temperatures below zero, the distortion of the reticle worsened accuracy by more than 20 MOA. EOTech delayed disclosing the defect for more than a year and until it had a fix in place. Even then, EOTech presented its fix to DOD as an upgrade to a quality product that already conformed to specifications.
In 2008, EOTech discovered that the sights leaked, allowing moisture to enter and cause a degradation of the reticle. Although the sights were always sensitive to humidity this became the number one reason for EOTech’s customer returns. EOTech waited to disclose the problem until 2013, when they believed they had arrived at a solution. And again, EOTech pitched its fix as an upgrade to a quality product that conformed to specifications.
Much of the information came to light after testing with the Norwegian Army revealed the issues with freezing temperatures and a rejection of EOTech’s bid due to the failures. Subsequent failures observed by US Special Forces troops training in Central America brought the leaky sights issue to light and internal communications suggest that EOTech chose to cover up these failures and fix them quietly while soliciting more bids.
The company settled out of court with the government for $25.6 million and is offering refunds to customers who feel that the sights were misrepresented to them. At the end of the day, it had to be the only honorable solution.
EOTech had a rather large booth at the 2016 SHOT Show in the law enforcement section. While the company is still offering holographic sights and magnifiers, the company focus seems to have shifted to variable power sights with traditional non-holographic reticles.
Personally, we will continue to use our EOTech as it performs the functions we need. However, we live in the High Sierras where humidity is low and if the temperature is below freezing, we try not to go shooting, or if we do, we use another sight. Owners of EOTech sights concerned about potential failure of their optics should contact the company for a refund.
As a recreational sight for a range gun they work fine. If the author were 20 years younger and kicking doors in for a living once again, we would probably go with another brand. However most will find that the EOTech Holographic sight will more than adequately fit their targeting needs.