I purchased an Eotech 512 sight and mounted it on my RRA A3 flat-rail, got a CG&G BUIS for the rear (standard A4 front), but having a problem with the sight picture.

It appears as though both the Eotech and BUIS (rear) would benefit from a riser mounted onto the flat-rail. As they sit right now, I can't sight the rear sight with the fron sight and the Eotech is too high in the sight picture (shouldn't it be right above the front sight when properly sighted in?). The only decent 'sight' I get is when I look down the barrell with the stock disengaged from my shoulder and my cheek resting against the rear collapsible stock. Consequently, it seems way too low.

Do I need to get a LaRue mount for the Eotech and rear sight? I thought that a flat stock would work without a riser in place...love the sighting of the Eotech (although it's a slight bit fuzzy for the laser ring, IMO) but as it stands now, this configuration isn't working....any suggestions?

Kurly

I think most people use risers of some sort or another.


Mine is on a .22 upper without any iron sights, so I didn't need one.

Hey Kurly,   The LaRue mount is definitely what you need.

I have no problem with my Eotech on the flattop, but I don't use a BUIS.

You might need a front sight adjustment tool if you can't get the elevation within range.

The Larue riser is for the EOTech.  You leave the rear BUIS on the top of the receiver rail...do not put it on the riser.  Are you saying that your rear sight and front sight aren't lining up?

You should be fine w/ mounting the 512 directly to your flattop for direct co-witness but the riser will allow you to have a 1/3 co-witness.  Also the rear rail on the Larue riser is for NVD mounts.  Not a BUIS.

Also for the fuzziness....look at the target, not at the dot/ring.

I've got an EOTech 552 standard A2 Front sight and an ARMS 40L on my set up.  No problems with sight picture at all.  I don't have a riser and I can't fore see a need for one IMHO.

I don't use risers at all.  Most of my Eotechs are mounted directly on the flattop's rail.  The one that isn't is mounted on top rail of the YHM free float tube, which is the same height.

I have no problems with either the irons or the Eotech.

Mounted directly to the flat top receiver is the only way to get co-witness with an EOTech. Are you aware that the holographic reticle is on target regardless of where it is in the window? Placing the riser under your BUIS will make zero impossible. Placing the EOTech on a riser will place your iron sights in the lower 1/3rd of the EOTech's window. One way to zero the EOTech is to sight-in your irons, then, while looking through your iron sights adjust the EOTech reticle to be where you want it (on top of the front sight post). Then fold away the rear BUIS and confirm zero with the Holographic sight alone.
Hope this helps.
Terry

This is how I set up my YHM & EOTech w/ GG&G Accucam mount:

Thanks fellas, I appreciate the input.  I've got my irons working okay, but I'm having problems getting the Eotech mounted.

Whenever I place it onto the rail, the Eotech doesn't want to lay flat -- there's about an 1/16" space between the bottom of the Eotech and the rail (on the side where the dovetail clamp is).  It just doesn't want to lay flat, even with the dovetail clamp adjustment screw backed all the way out.

I'm reluctant to for the side down for fear of scratching the mount or Eotech.  In looking at the dovetail clamp, shouldn't the clamp have the same contour as the Eotech's rail?  Mine has the long edge of the clamp coming out first, almost like it's upside down.

I'm sure I'm overlooking something but I've tried everything and it still won't lay level.  Any suggestions appreciated.

height=8

Quoted: Thanks fellas, I appreciate the input.  I've got my irons working okay, but I'm having problems getting the Eotech mounted. Whenever I place it onto the rail, the Eotech doesn't want to lay flat -- there's about an 1/16" space between the bottom of the Eotech and the rail (on the side where the dovetail clamp is).  It just doesn't want to lay flat, even with the dovetail clamp adjustment screw backed all the way out. I'm reluctant to for the side down for fear of scratching the mount or Eotech.  In looking at the dovetail clamp, shouldn't the clamp have the same contour as the Eotech's rail?  Mine has the long edge of the clamp coming out first, almost like it's upside down. I'm sure I'm overlooking something but I've tried everything and it still won't lay level.  Any suggestions appreciated.

FWIW, I thought I'd share an update with everyone in case someone else has a similar problem.  I'm unable to get the Eotech to lay flat on the stock flat rail -- the hand guard rail fits fine, but is too far away.  The stock, flat rail I have appears to be slightly out of spec.  It's a RRA but that's the only thing I can think of if the hand rail mounts I added work fine.  I talked with the person I bought it from and he did mention that there was one other occasion where he had a buddy of his that wouldn't mount correctly either.  Thinking about sending the upper back to RRA for replacement since it hasn't been fired yet, but hate to go through all the hastle.  Other option is just to return the Eotech and purchase something else instead.  

Has anyone tried the RRA Dominator2 riser with the EOTech?  It has the A2 rear sight. It says it will raise the reticle above the front sight and then you can use your Iron sights through the bottom of the EOTech window.

I have a Dominator1 riser for my 512 and I love it.  It allows a lower co-witness and keeps the standard A2 rear site.  That was important to me because when I went thru the Dept patrol rifle school I wanted the same rear sight as the issued rifles had...makes  training easier.

Hey put the tip of your nose on the charging handle

it seems wrong but the 512 with no riser sits exactly as high as the carry handle

GG&G cowitness well however proper sight picture is a must with BUIS

get your head lower to the rifle

Well I received a replacement 512 from Eotech the other week.  Dennis said that they've had a few problems with their mounts and RRA and Busmaster rails.  Said they would replace it with a different clam shell that was supposed to cause it to seat correctly.  

Unfortunately it didn't work.  It's still sitting at about a 5 degree cant.  I contacted Eotech again and said that it still wasn't siting properly and they said I could send it in, doubted that they could do anything, and that it's probably the RRA.  NOT happy with their service...Back it goes to the dealer -- gonna look at Aimpoints.

Quoted: Well I received a replacement 512 from Eotech the other week.  Dennis said that they've had a few problems with their mounts and RRA and Busmaster rails.  Said they would replace it with a different clam shell that was supposed to cause it to seat correctly.   Unfortunately it didn't work.  It's still sitting at about a 5 degree cant.  I contacted Eotech again and said that it still wasn't siting properly and they said I could send it in, doubted that they could do anything, and that it's probably the RRA.  NOT happy with their service... Back it goes to the dealer -- gonna look at Aimpoints.

FWIW, RRA has had some out of spec uppers at times in the past. It may be the upper. If two different Eotechs don't fit right it might be the upper. Check with RRA.

height=8

Quoted: height=8 Quoted: Well I received a replacement 512 from Eotech the other week.  Dennis said that they've had a few problems with their mounts and RRA and Busmaster rails.  Said they would replace it with a different clam shell that was supposed to cause it to seat correctly.   Unfortunately it didn't work.  It's still sitting at about a 5 degree cant.  I contacted Eotech again and said that it still wasn't siting properly and they said I could send it in, doubted that they could do anything, and that it's probably the RRA.  NOT happy with their service...he FWIW, RRA has had some out of spec uppers at times in the past. It may be the upper. If two different Eotechs don't fit right it might be the upper. Check with RRA.

Not a bad suggestion -- pain in the ass to deal with, but a good suggestion.  Do I need to go back through the dealer or can I go direct to RRA?  I imagine they'd want to see it anyway.

Quoted: Has anyone tried the RRA Dominator2 riser with the EOTech?  It has the A2 rear sight. It says it will raise the reticle above the front sight and then you can use your Iron sights through the bottom of the EOTech window.

Here is my RRA with EoTech and Dominator 2.  It works perfectly.  The iron sights cowitness in the lower third of the Eotech.