Eotech has very specific info: http://www.eotech-inc.com/counterfeit_notice.php , but not everyone who gets ripped off has as much detailed information as they do.
(PDF file download link)
http://www.eotech-inc.com/documents/Recognizing counterfeit EOTech Sights 4-09.pdf
Trijicon Optics (ACOGS)
Call or e-mail Trijicon with the model number and serial number to verify if it's authentic or a knock-off scope. Knock-offs tend to have the same serial number on all of them.
email@example.com or at (800)338-0563
Customer Service Hours
M-F 9:00 a.m. - 5:00 p.m. EST
Some conventional wisdom for identifying fake ACOGs:
- Should have the digital square.
- "Tririum" = fake.
- A real ACOG will have tritium and be illuminated in the dark.
Troy Industries Sights
The most common differences
1.Most Airsoft copies are castings so they have so they will have Zinc in them which makes them heavier than the aircraft aluminum we use.
2. also being a casting look for seam lines in places such as the middle of the peep, downt he center of the sight tower, and on the base parrell with the sight mounting screw.
3. Look for the roll pin that hold the base of the sight to the sight tower, most airsoft sights are a metal dowel.
4. The peep adjustment threads are course on most copies. you will see only 2 to 3 threads and they will stop short of the protective ears on the upper tower.
5.The clamping screw should only be threaded on the end. Some airsoft sights the screw is threaded the entire way.
6. Most airsoft sights are painted where ours is anodized. you will notice the finish wearing off quickly on a airsoft sight. This also gives the sight a sticky feeling when pushing in the release button or moving the sight town up and down.
There are a few different types of fakes out there. some may have these features and some may not. Each year I find copies that look closer to the real thing but one thing that has never changed is the cheap metal they use.