Eotech 512 Hand Guard Interference

BWDuty · March 9, 2014, 01:44 AM

Hi everybody, and thank you for taking the time to read my thread!

I'm new here, and a proud owner of an AR15 configured as an M4. I spent quite a bit of time getting it just the way I want it, but have just come across what might be a problem.

I pretty much customized it from scratch. It is a Smith and Wesson M&P 15 lower, a Hogue grip, a Rock River Arms telescoping stock, a CMMG 14.5" upper with welded phantom flash suppressor, a Tapco T6 buttpad, a Fire Force 3 point sling, an EOTech 512 holographic weapons system, and a Matech flip up BUIS.

My (potential) problem is that I didn't realize how badly I was limiting myself by getting the 14.5" barrel with the welded flash suppressor. I did some research, but not enough. CMMG was a local company for me (I'm from Missouri), the 1:7 twist chrome lined barrel seemed good, and it just plain looked cool.

It has a pretty basic carbine length handguard. When I place my EOTech 512 sight on the picatinny rail, if I leave enough room behind it for the BUIS and to access the buttons on the EOTech, the front of the EOTech extends slightly over the top of the handguard. I expected that. What I didn't expect is that the handguard sits *very* slightly higher than the sight, causing a *very* slight incline.

Will this throw off my sight picture, or does the holograph somehow compensate? Ideally I would just replace the handguard with a quad rail that sits a bit lower, but can this be done (if I find one the exact same length and use the same gas block from my front sight) without cutting off the flash suppressor? The handguard appears to be two pieces so I'm wondering if they can just come apart once the front sight is removed and a new one "dropped in". My only other options are to move the EOTech back a bit and not use the BUIS, or buy a new upper I suppose. Any suggestions, or is it ok as is?

I know I can adjust the elevation on the EOTech of course to compensate, but will the slight incline be an issue with maintaining zero at varying distances?

And just out of curiosity, even if that is the case, do I have any options to replace the hand guard?

camoman621 · March 10, 2014, 07:59 AM

The Eotech will probably self correct for a slight incline. One option would be to replace the handguard with a Magpul MOE handguard which I beleive has clearance grooves on the top of the guard to remedy your specific problem. Another solution if possible would be to exchange the AA battery Eotech for the lithium battery model which is shorter thus allowing you to install it more forward on the rail. Good luck.

Willie Lowman · March 10, 2014, 11:23 AM

If it were my rifle I would get some sand paper and remove plastic till there was no pressure on my sight.

Or change the handguard.

Quote:

do I have any options to replace the hand guard?

Let's see what google can find

BWDuty · March 16, 2014, 07:58 AM

Thanks for the suggestions! I think I might have answered my own question. I was lying in bed and it hit me.. I wonder if they make elevated rails? A quick Google search shows that they do! A Picatinny rail that goes on top of a Picatinny rail. A thin one of these will raise my EOTech high enough to clear the handguard and remain level, while keeping everything looking original. I think I'll go that route!

Ridge_Runner_5 · March 16, 2014, 10:11 PM

They make risers specifically for EOTechs, but that changes your sight picture.

A cheaper option would be Magpul MOE handguards. Nowadays they actually have cutouts on the rear side to allow for the EOTech to sit over them properly.

nemesiss45 · March 16, 2014, 10:32 PM

You all have too much money to throw arround. Im with willie. If it were my rifle, id hit the hand guard with sand paper or the dremel and adjust the offending section. It looks like only a fraction of an inch... why spend $50+ to fix it?

Ridge_Runner_5 · March 17, 2014, 05:45 PM

Quote:

why spend $50+ to fix it?

$30
http://store.magpul.com/product/MAG440/184

And it's reversible if you decide you don't like it/need it or change optics down the road. Plus the ability to add things such as lights or forward grips easily.

nemesiss45 · March 17, 2014, 10:11 PM

hmm, those are pretty cheap. I hear magpul and think $$$.I might look at those for my AR

March 9, 2014, 01:44 AM	#1
BWDuty Junior Member Join Date: March 9, 2014 Posts: 2	Eotech 512 Hand Guard Interference Hi everybody, and thank you for taking the time to read my thread! I'm new here, and a proud owner of an AR15 configured as an M4. I spent quite a bit of time getting it just the way I want it, but have just come across what might be a problem. I pretty much customized it from scratch. It is a Smith and Wesson M&P 15 lower, a Hogue grip, a Rock River Arms telescoping stock, a CMMG 14.5" upper with welded phantom flash suppressor, a Tapco T6 buttpad, a Fire Force 3 point sling, an EOTech 512 holographic weapons system, and a Matech flip up BUIS. My (potential) problem is that I didn't realize how badly I was limiting myself by getting the 14.5" barrel with the welded flash suppressor. I did some research, but not enough. CMMG was a local company for me (I'm from Missouri), the 1:7 twist chrome lined barrel seemed good, and it just plain looked cool. It has a pretty basic carbine length handguard. When I place my EOTech 512 sight on the picatinny rail, if I leave enough room behind it for the BUIS and to access the buttons on the EOTech, the front of the EOTech extends slightly over the top of the handguard. I expected that. What I didn't expect is that the handguard sits very slightly higher than the sight, causing a very slight incline. Will this throw off my sight picture, or does the holograph somehow compensate? Ideally I would just replace the handguard with a quad rail that sits a bit lower, but can this be done (if I find one the exact same length and use the same gas block from my front sight) without cutting off the flash suppressor? The handguard appears to be two pieces so I'm wondering if they can just come apart once the front sight is removed and a new one "dropped in". My only other options are to move the EOTech back a bit and not use the BUIS, or buy a new upper I suppose. Any suggestions, or is it ok as is? I know I can adjust the elevation on the EOTech of course to compensate, but will the slight incline be an issue with maintaining zero at varying distances? And just out of curiosity, even if that is the case, do I have any options to replace the hand guard? Last edited by BWDuty; March 9, 2014 at 01:54 AM.

March 10, 2014, 07:59 AM	#2
camoman621 Junior Member Join Date: March 11, 2013 Posts: 6	The Eotech will probably self correct for a slight incline. One option would be to replace the handguard with a Magpul MOE handguard which I beleive has clearance grooves on the top of the guard to remedy your specific problem. Another solution if possible would be to exchange the AA battery Eotech for the lithium battery model which is shorter thus allowing you to install it more forward on the rail. Good luck.

March 16, 2014, 07:58 AM	#4
BWDuty Junior Member Join Date: March 9, 2014 Posts: 2	Thanks for the suggestions! I think I might have answered my own question. I was lying in bed and it hit me.. I wonder if they make elevated rails? A quick Google search shows that they do! A Picatinny rail that goes on top of a Picatinny rail. A thin one of these will raise my EOTech high enough to clear the handguard and remain level, while keeping everything looking original. I think I'll go that route!

March 16, 2014, 10:11 PM	#5
Ridge_Runner_5 Senior Member Join Date: February 8, 2008 Location: Denver, CO Posts: 1,925	They make risers specifically for EOTechs, but that changes your sight picture. A cheaper option would be Magpul MOE handguards. Nowadays they actually have cutouts on the rear side to allow for the EOTech to sit over them properly.

March 16, 2014, 10:32 PM	#6
nemesiss45 Senior Member Join Date: February 6, 2014 Posts: 526	You all have too much money to throw arround. Im with willie. If it were my rifle, id hit the hand guard with sand paper or the dremel and adjust the offending section. It looks like only a fraction of an inch... why spend $50+ to fix it?

March 17, 2014, 10:11 PM	#8
nemesiss45 Senior Member Join Date: February 6, 2014 Posts: 526	hmm, those are pretty cheap. I hear magpul and think $$$.I might look at those for my AR