I recently got an Eotech 512 HWS (holographic weapon sight) in a scope swap with Korium on this forum a while ago. As I'm ex military I tend to have a penchant for military issue optics and tacticool stuff, so one of these was on my list of things that I must own. Mine was made in March 2013 and is the currently manufactured model as far as I'm aware, with the forward relief cut under the front of the sight for use with full length picatinny top rail systems.

Bushnell were the originators of the holographic weapon sight, then Eotech started to produce their own more rugged version, presumably by paying Bushnell a wad of cash for the rights to the technology as the guts of the Eotech series and the current Bushnell Holo sights are produced in the same factory. As far as I'm aware, only the Eotech is in military service, and worldwide too. Even us Brits use them, with the Army and Marines having them on shotguns and for other specialized applications, and they are widely used by police forces in the U.K.

The 512 is probably the most common of the Eotech range. It runs off two AA batteries that are widely available in any corner shop in any country in the world. It's construction is of plastics with an aluminium shroud, however it's built to last, Eotech sights have actually been shot in warzones and have still continued to function.

Its reticule is a 65 MOA circle with vertical and horizontal aiming marks, with a 1 MOA dot in the centre. 65 MOA at 100 meters is roughly the size of the average male human at the same distance, the reticule was deliberately designed this way to allow the user to use the sight as a simple rangefinder. So for example, a human sized target fills the circle, the user knows they are roughly 100m away. If the same target only fills half of the circle, from the dot to the top of the circle for example, the user knows the target is roughly 200m away. It's a simple and ingenious system.

The reticule has 12 different brightness levels. On the 512, the night vision button is blanked off. All the night vision mode does is light the reticule at such a low level that the human eye can't see it, however it is visible when looking at the reticule through a night vision device. The 552 model which otherwise is identical to the 512 has the night vision feature and has a button marked NV on the sights controls. The 512 can be used with older night vision equipment if the reticule is set to it's lowest brightness setting, however this is too bright for current night vision equipment and it will damage current generation night vision gear.

To turn the sight on you can either press the left "down" button (turns on sight for 4 hours) or the right "up" button (turns sight on for 8 hours). The reason the sight has an auto off function is to prevent battery power loss, especially if the host weapon is stored and the user forgets to turn the sight off. To turn the sight off, press both the "down" and "up" buttons at the same time.

The optic comes in a good quality plastic box with cardboard sleeve. The box has holes moulded into its body so it can be zip tied or padlocked shut.
http://i978.photobucket.com/albums/a...ps86040f12.jpg

Eotech 512 mounted on a .357 Marlin 1894CS carbine. Traditionalists will hate me for doing such a thing, and John Wayne must be turning in his grave, but I don't care, it's a surprisingly excellent and practical combination.
http://i978.photobucket.com/albums/a...psb1cb53a4.jpg

Eotech 512 right side with adjustment screws.
http://i978.photobucket.com/albums/a...ps7f0352f5.jpg

Eotech 512 left side with "For Law Enforcement/Military Use" written on the side.
http://i978.photobucket.com/albums/a...psd79450a2.jpg

Eotech 512 showing the reticule and control buttons. The centre round moulding is where the NV button is present on NV compatible models such as the 552.
http://i978.photobucket.com/albums/a...pse602e3de.jpg

Personally I think it is an excellent optic for short range target shooting up to 100m/200m. Anything further would benefit from a conventional rifle scope, however for short range the Eotech can't be beat. Although unconventional to look at, it does marry up well with an underlever carbine to create a "scout gun", or on an AR15 for close range targets, as this is the type of application for which it excels at.