Strange Eotech problem

[mattmcg]

So, I'm having a really strange problem on a new Eotech 512 that I'm adding to a CMMG middy upper with an F marked FSB. BTW, I'm using a Troy foldable rear sight.

My plan is to mount the 512 directly on the rail and have an absolute co-witness with the FSB and rear iron sights. The problem is, the Eotech 1 MOA dot is no where near the proper aiming plane! The red dot and circle are far below the aiming path from the rear BUIS to the FSB! I then tried adjusting the elevation and ran into the stop and still wasn't able to get the dot to co-witness! Very strange and I'm wondering if I am doing something wrong or if the Eotech is defective.

Does anybody have any good advice on this? Is this a known issue with Eotechs?

Thanks..............

[Boomer10]

The Jan. '08 issue of SWAT has a great article titled "Running the Red Dot Right" and it explains how to properly cowitness iron sights with red dot sights (specifically Aimpoints and Eotechs).

The article was by Pat Rogers so I'm assuming he may pop in here to give you more input.

[Erick Gelhaus]

You'll have to use the article. For reasons I'm not aware of Pat has been PNG'd from this board.

[rhino]

So, I'm having a really strange problem on a new Eotech 512 that I'm adding to a CMMG middy upper with an F marked FSB. BTW, I'm using a Troy foldable rear sight.

My plan is to mount the 512 directly on the rail and have an absolute co-witness with the FSB and rear iron sights. The problem is, the Eotech 1 MOA dot is no where near the proper aiming plane! The red dot and circle are far below the aiming path from the rear BUIS to the FSB! I then tried adjusting the elevation and ran into the stop and still wasn't able to get the dot to co-witness! Very strange and I'm wondering if I am doing something wrong or if the Eotech is defective.

I've mounted two pretty much the same way (although I have GG&G and MI rear sights) successfully (but with a bit of a detour mentioned below) each time. That doesn't help you with your problem, but it is a baseline for how it probably should work.

Question ... are you looking through the iron sights to see where the dot is? For your preference, the red dot should "sit" on top of the front sight post (which you probably already know).

I'm going to ask this with good intentions, so don't think I'm trying to insult you. Are you using the elevation adjustment properly? Turning in the "up" direction shifts the point of impact of your rounds upward, but the dot itself will move downward in the screen. If your dot is too high in the reticle, you actually need to turn it "up" so that the dot itself moves downward. If the dot is in the lower part of the screen, you need to turn elevation "down" which will cause the dot to move upward.

I know how confusing this can be because I did exactly what I think you did. It took me a few minutes of thinking before it dawned on me that I was moving the dot in the wrong direction (I reached the end of the adjustment as well), then when I cranked the other way, I saw immediately how it worked. If you look through the EOTech while you turn the elevation screw, you can see it.

If that isn't the problem, I'd call EOTech customer service. They may be able to talk you through something to determine if you need to do something else or if it's a defective scope.

Good luck!

[Treehopr]

So, I'm having a really strange problem on a new Eotech 512 that I'm adding to a CMMG middy upper with an F marked FSB. BTW, I'm using a Troy foldable rear sight.

My plan is to mount the 512 directly on the rail and have an absolute co-witness with the FSB and rear iron sights. The problem is, the Eotech 1 MOA dot is no where near the proper aiming plane! The red dot and circle are far below the aiming path from the rear BUIS to the FSB! I then tried adjusting the elevation and ran into the stop and still wasn't able to get the dot to co-witness! Very strange and I'm wondering if I am doing something wrong or if the Eotech is defective.

Does anybody have any good advice on this? Is this a known issue with Eotechs?

Thanks..............

Did you have any problems zeroing the Troy sight and FSB?

Is the CMMG middy upper new?

Sometimes uppers can be improperly assembled and have problems such as canted receivers or FSB's.

[Stickman]

mattmcg,



Have you test fired the weapon using the iron sights?

[mike240]

You'll have to use the article. For reasons I'm not aware of Pat has been PNG'd from this board.

What is "PNG"?

[Tom_Jones]

deleted

[mattmcg]

Question ... are you looking through the iron sights to see where the dot is? For your preference, the red dot should "sit" on top of the front sight post (which you probably already know).

Yes, that is exactly what I'm doing. Looking through the rear BUIS to the post on the front FSB and seeing the Eo dot lower than the aiming plane

I'm going to ask this with good intentions, so don't think I'm trying to insult you. Are you using the elevation adjustment properly? Turning in the "up" direction shifts the point of impact of your rounds upward, but the dot itself will move downward in the screen. If your dot is too high in the reticle, you actually need to turn it "up" so that the dot itself moves downward. If the dot is in the lower part of the screen, you need to turn elevation "down" which will cause the dot to move upward.

Yes, I thought this one through and turned the elevation screw to move the red dot up in the sight picture. I even double checked it by turning it the other way to confirm that it was moving lower in the sight picture when turned the other way.

If that isn't the problem, I'd call EOTech customer service. They may be able to talk you through something to determine if you need to do something else or if it's a defective scope.

I'm beginning to suspect that may be my problem but thought I would troubleshoot with you fine folks to get to the bottom of it.

[mattmcg]

mattmcg,



Have you test fired the weapon using the iron sights?

Yes, the rifle has been tested with the iron sights and it is hitting where it should using iron sights.