Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Arrow Left Previous Page
Page / 2
Posted: 8/16/2004 10:15:27 PM EST
I took my Aimpoint/ARMS mount off my carbine for use on a shotgun.

I mounted the EOTech on the flat top rail and looked through the iron sights. The EOTech reticle is about 1/4" low and 1/4" left of where it needs to be (it could be as much as 1/3" off in both directions.

How do I get it sighted in (cowitnessed) without using all the windage and elevation adjustment? It may even be beyond their ability to center the reticle. Is this common? Anyone else have this problem?

Link Posted: 8/16/2004 11:32:24 PM EST
Get the LaRue Tactical EOthing mount. It will solve your problem.
Link Posted: 8/17/2004 3:25:25 AM EST
Link Posted: 8/17/2004 3:59:06 AM EST
I had the same problem when I installed a set of Troy Inds BUIS's on my AR..

1/4 low & 1/4 left. How could that be you ask

Two reasons....

First, I found that my free float handguard wasn't perfectly aligned with the flat top receiver. The folding front sight (short version) was mounted on the handguard (not the gas block).

Secondly, I found that my "cheek-weld" significantly changed when I installed my new LMT Crane stock

Link Posted: 8/17/2004 3:59:38 AM EST

Originally Posted By C4iGrant:
The LaRue EOTech will solve the 1/4 low problem and will also give you 100% repeat zero.

C4

www.gandrtactical.com


www.gandrtactical.com/images/archive/LaRue%20EOTech%20%20ECOS.jpg



Dangit! I can't wait to pick up my LaRue mount!
Link Posted: 8/17/2004 6:35:58 AM EST
Are you serious? Do I really need to spend more ka-ching, ka-ching for more bling bling?

I think I will try shimming first. I do not like the concept of shimming but if the offset is due to a small angular displacement it might be okay. Even if successful, the irons are very high in the EOTech window, obscuring a large part of the field of view. The LaRue would raise the sight by 1/2" (?), simultaneously solving both problems.

I do not typically remove my sights. That feature of the LaRue oes not sway me.

The problem does not derive from a handguard misalignment. My front sight is mounted on my barrel and has been zeroed. The rear is an LMT BUIS.

C4iGrant, sounds like we'll be talking again very soon.
Link Posted: 8/17/2004 6:51:10 AM EST
Link Posted: 8/17/2004 9:34:02 AM EST
Please forgive my forgetfulness, I know it has already been discussed but could someone remind me what ECOS-C stands for.
Link Posted: 8/17/2004 9:50:15 AM EST
Link Posted: 8/17/2004 11:33:30 AM EST

Originally Posted By Mike_Mills:
How do I get it sighted in (cowitnessed) without using all the windage and elevation adjustment? It may even be beyond their ability to center the reticle.


How do you know it is beyond the ability to center the reticule - Have you tried (it sounds like you haven't).

Stop worring about 'what ifs' and just zero the MoFo; you'll find out if you have enough adjustment or not (I'll bet you will have enough).
Link Posted: 8/17/2004 12:41:43 PM EST
any way to mount the eotech on the receiver with a RAS II hump and KAC BUIS?
Link Posted: 8/17/2004 3:11:34 PM EST
[Last Edit: 8/17/2004 3:12:43 PM EST by Mike_Mills]
The reticle appears to be 0.25" or even 0.35" off center at the distance of the front sight (18" away). That is the equivalent of being approximately 0.20" per foot of distance. That equates to 60" (60 MOA) off target at a distance of 300 feet (100 yards).

EOTech lists only +/- 40 MOA of MOA of adjustment via the windage and elevation screws. Bummer!
Link Posted: 8/17/2004 5:02:35 PM EST
Are you certain that your front sight is not rotated off plumb? It's really pretty common and easy to fix.

Luck,

SD
Link Posted: 8/17/2004 8:19:34 PM EST
The front and rear BUIS co-witnesses with the Aimpoint pefectly. When I replace the Aimpoint with the EOTech and sight through the irons the EOTech reticle is way off the mark.
Link Posted: 8/19/2004 10:34:32 PM EST

Originally Posted By C4iGrant:

Originally Posted By BH1:
Please forgive my forgetfulness, I know it has already been discussed but could someone remind me what ECOS-C stands for.



Enhanced Combat Optical Sights


C4


Thanks C4. What about the -C? Enhanced Combat Optical Sight - Carrier? Just a guess.

Sorry to hijack your thread Mike.
Link Posted: 8/20/2004 2:46:28 AM EST
I have you tried to go to the range with it to see if it really off and by how much? You keep saying it 'appears" and "It seems" which sounds like you haven't actually zeroed at the range.
Link Posted: 8/20/2004 1:07:08 PM EST

Originally Posted By BH1:

Thanks C4. What about the -C? Enhanced Combat Optical Sight - Carrier? Just a guess.



The -C in ECOS-C is for Carbine.
Link Posted: 8/20/2004 3:36:14 PM EST
knightone,

When I used the word "appears", I meant it in the context of as observed by the human eye, or as seen by using your eyes. Remember, EOTechs don't actually project a red dot forward. The dot "appears" to be on the target as seen by the shooter. In actuality, it is not.

I haven't zeroed it at the range. There is no doubt in my mind point of aim will be waaaay off point of impact. When I installed the Aimpoint sight, its red dot landed atop the post as soon as I tightened the ARMS mount locking lever. Sure enough, it shot to the same POI as the iron sights.

The only uncertainty I have lies in how far off the dot appear to be (I did not measure it with a ruler but could have). I have a hooded front sight with a post insert on my carbine. The red dot appears on the edge of the hood rather than atop the post where it should be.

i hope this clarifiews things.
Link Posted: 8/21/2004 3:10:48 AM EST
I'VE BEEN TOLD THAT YOU SHOULD MEASURE HOW TALL YOUR FRON POST IS. IT SHOULD BE (BY INFO I HAVE GATHERED) AROUND 1.350", 1.40" TO 1.570" IN HEIGHT. YOU SHOULD MEASURE THE BOTTOM OF THE OPTIC TO THE CENTER OF THE RETICLE AND TAKE THAT MEASUREMENT AND SUBTRACT FROM THE HEIGHT OF THE FRONT POST. THIS WILL TELL YOU HOW TALL YOUR RISER NEEDS TO BE (LOOKS GOOD ON PAPER). FOR EXAMPLE A 1/2" RISER EQUATES TO .500". RISERS AREN'T THAT EXPENSIVE. CK IT OUT, THIS SHOULD SOLVE ONE OF YOUR ISSUES. I'VE BEEN DOING A LOT OF RESEARCH ON THIS MY SELF, AND HAVEN'T GOT MY OPTIC MOUNTED YET (WAINTING ON A RISER I ORDERED FROM CMMGINC.COM). IF THIS DOESN'T WORK FOR ME WITH THE OPTIC I HAVE PICKED OUT THEN I'M GOING TO GET AN EOTECH. SO PLEASE LET ME KNOW HOW THINGS WORK OUT.
Link Posted: 8/22/2004 10:41:05 AM EST
My point was that you will nver know how far off paper it is unitl you try and zero it with live ammo. If you can't get it to zero there, then get in touch with EOTech. EOTech has excellent customer service. Well, so I a m told. I have never had a problem with any of their sights. If there is something wrong with the unit, just get in touch with thema nd they will take care of you right away.
Link Posted: 8/22/2004 2:56:17 PM EST
I have installed EOtechs with YHM, Arms, BMAS(YHM), and GGG rear back ups without any cowitnessing problems. This is with standard FSB's and mounted to the flat top upper. I had issues with one rifle when he mounted the EOtech to a Surefire foregrip which sets alot lower than the flat top itself. Problem solved with a YHM riser....

Cheers

-Belial
Link Posted: 8/23/2004 6:14:44 PM EST
[Last Edit: 8/23/2004 6:15:15 PM EST by Mike_Mills]
knightone,

"...you will nver know how far off paper it is unitl you try and zero it with live ammo..."

I beg to differ. The irons are already mounted and zeroed. The rifle is zeroed. The EOTech's dot needs to on top of the front post or it will not shoot to the EOTech's point of aim. There is no way the EOTech can be 1/3" off in both directions and have it shoot to point of aim. That's a test I do not need to run.

Link Posted: 8/23/2004 6:22:40 PM EST
C4iGrant,

I received the LaRue mount today. There's a problem. It does not fit on the remaining rail space in front of my LMT rear sight. Honestly, it doesn't really fit the EOTech too well, either. The throw lever bangs into the EOTech housing when only partially opened such that the lever cannot be fully opened.

One advantage of the EOTech was supposed to be cost, the Aimpoint requiring an expensive mount in addition to the cost of the sight. If I need this fancy LaRue mount to make the EOTech work (co-witness with the iron sights) the supposed cost advantage is totally lost. Without the mount a performance advantage is lost (can't co-witness).

This is a pain.

As of now, I'm thinking the Aimpoint is winning the battle rather than EOTech. Perhaps you can help me out and allow the EOTech to catch back up.
Link Posted: 8/23/2004 6:31:50 PM EST
[Last Edit: 8/23/2004 6:35:23 PM EST by brassburn]
?? I have 4 LaRue products, including the Eotech mount. They all are exemplary products. I have no such problems with the LaRue EOTech mounts, nor have I seen any from other AR15.com members. I wonder if there isn't another problem at play here? Grant is the man no matter what. I don't buy from anyone else so I am sure he and/or other members would be more than happy to help you out.

EDIT**

BTW knightone is 100% correct. I don't care how dialed in your irons might be. Optics, or any other sighting system should never be zeroed on anything but paper. Thinking you can truly zero an optic by positioning the aiming point on your irons is (no offense) foolish.
Link Posted: 8/23/2004 7:30:28 PM EST
[Last Edit: 8/23/2004 7:32:22 PM EST by Mike_Mills]
Okay, guys, get off it. I don't need live fire to KNOW this EOTech is nowhere near zeroed. If we were talking about dialing it in, I'd agree with you 100%. This EOTech is pointing 100" low and another 100" left of the point of impact at 100 yards - not even close.

I do need some help with that other factor which is at play - my ignorance of this new LaRue mount and how to fit it in combination with my LMT rear BUIS. If anyone can help me with that, please do so.

I hesitate to remove the LMT but might remove it in order to try and find a compromise position for the two on a single receiver-sized rail. I have the LMT mounted flush with the rear end of the receiver rail. How far off the rear end of the receiver should a rear sight extend?


P.S. - Grant did a great job of getting three major items to me in less than a week, one of which was out of stock (the LaRue). Good job, Grant, you da man!
Link Posted: 8/23/2004 10:03:26 PM EST
I got a new EOtech on Friday, as well as a ARMS #40 flip up iron sight. Mounted directly onto a RRA flat-top upper. Off to the range Saturday. At the 50 yard range:

First I zero'd the iron sights. They were about 4" high and an inch to the right. Got that sorted out pretty quickly.

Then turned on the EOtech. Looking at a 50 yard NRA slow fire pistol target (24x21") with the iron sights on the center the EOtech was pointed almost at the bottom left corner of the paper. When I aimed the EOtech at the center and fired the bullet missed the target (high and right).

Well some cranking on the adjustments and about 20 shots later I was hitting the center.

Conclusion after reading this thread is that on a standard flat-top upper maybe the EOtech isn't quite right. But there appears to be more than enough adjustment available to zero it. Now I can either co-witness or just leave the rear sight down and look above the front post.

madkiwi
Link Posted: 8/24/2004 2:58:13 AM EST
Link Posted: 8/24/2004 7:14:58 AM EST
This is messed up.

I have an EOTech that is pointing at something other than the target and a mount which doesn't fit my upper.

BUMMER!
Link Posted: 8/24/2004 7:43:26 AM EST
Link Posted: 8/24/2004 9:07:03 AM EST
Hi Grant,

The iron sights are just at their nominal settings, nothing is cranked over either way.

I started by zeroing an Aimpoint on an ARMS mount. It was on paper right out of the box and only minor fine tuning of windage and elevation were necessary to center the group. I have been able to remove and replace the Aimpoint without loss of zero.

The LMT rear sight basically just drops onto the receiver. It fits well and looks like part of the rifle.

I installed and leveled the front sight (relative to the receiver). I sighted through the rear aperture and, low and behold, the top of the post was lined up with the Aimpoint red dot.

Once again, only fine tuning of windage and elevation were necessary when I got to the range (using the LMT rear sight's adjustments).

Clearly, the LaRue works with the upper but not with the rifle configured the way it is. This LMT sight is great, too bad they did not make thier mount compatible with it. It is so close to fitting, too. If they had placed the ball detent about 1/4" to 1/2" farther to the rear it would fit. I don't believe this minor redesign would adversely impact functionality in any way. They should have provided some clearance between the throw lever and the sight, too. Again, 0.010" to 0.020" clearance wouldn't hurt anything and it would be a better design.
Link Posted: 8/24/2004 9:17:41 AM EST
Link Posted: 8/24/2004 10:25:37 AM EST
Grant,

I wasn't implying they should shave down the lever rather where/how it's mounted. It's not worth any further discussion, - it is what it is.

I have more work to do tonight - fitting and checking the EOTech, etc. I guess it seems to me it is the EOTech unit that is out of whack. If I find out why it sits so cock-eyed relative to the other things on the rail, I might be able to fix the root cause and not need to mess with the LaRue mount. Perhaps my EOTech is defective or I've installed it incorreclty, etc.
Link Posted: 8/24/2004 10:27:32 AM EST
Link Posted: 8/24/2004 3:25:53 PM EST
I'm not trying to be a smart -ass, but when I got my EO-Thingy, it was way off from my zeroed iron sights, all you have to do is adjust your dot to the top of the post! All you can do is give it a try.

Surely you weren't expecting it to be pre-zeroed just because your Aimpoint happened to be?
Unless I'm missing something here, if so I apologize, I don't see what the problem is.

teamroper2004
Link Posted: 8/24/2004 4:00:52 PM EST
You're not missing it. The thing is, it's so far off the range of adjustment does not allow centering the reticle. It is 100 MOA left and 100 MOA low*. The sight has only 40 MOA of adjustment.

The more we discuss this the more I know something is not right. I'm going to work this problem so more tonight. I'll let you know what happens.

* note: 1/3" off center at a distance of 1 foot = 100" at 300 feet (100 yards) => ~ 100 MOA
Link Posted: 8/24/2004 6:09:46 PM EST
Have you tried to adjust it? I just ask because your post doesn't make this clear to me( could just be me though)

If so and it still won't co-witness, it's either mounted wrong( which I really don't see possible) or there's something wrong with the EO-thingy.

You shouldn't have to use the LaRue mount to co-witness.

teamroper2004
Link Posted: 8/25/2004 4:43:59 AM EST
[Last Edit: 8/25/2004 4:47:43 AM EST by Yojimbo]
Mike,

Try to adjust the dot and move it right on the tip of your front sight post when looking through the irons. Before getting all worried about your sight give this a try first and let us know how it goes.

Seriously, it's a rare occurance that an optical sight is dead on when it's first mounted. The method above is what I used to get my EOTech 552 dialed in right from the box, granted you need to have your irons properly zeroed. Once you've done this you need to confirm the EOtech's zero on the range and fine tune it if needed.
Link Posted: 8/25/2004 9:55:44 PM EST
Well, guys, I did it. I fixed the problem. The EOTech is now aligned with my iron sights.

All of you were correct, just go ahead and line the dot up with the front post when sighting through the iron sights. I did it, it worked.

There were two compounding problems - the adjustment dials were no where near centered and the sight does have a bit of a tilt to it. I started out by setting them at their mechanical centers. Then I moved them to center the dot on the post.

There's nothing I can do about the tilt, short of sending the unit back to EOTech or shiming or whatever. The thing is, this sight is not set up for dialing in windage and elevation changes. It's intended for CQB - fast shooting. Elevation and windage offsets changes needed for long range shots or windy days will have to be achieved by holding off/over. Given these facts, it doesn't matter how much windage remains after zeroing the sight.

The dials don't need to be centered. You set them and forget them. It worked, I'm in business.



I do not need and canoot use the LaRue mount I purchased on my AR as it is currently configured. I might move this EOTech to my self-defense shotgun. Perhaps it is there I will use the LaRue mount, perhaps not.

I do think I prefer an Aimpoint for the shotgun. Perhaps I will move the TROY rear, flip up BUIS to the AR-15 and use the EOTech on the LaRue mount after all. I can put the LMT rear sight on the shotgun, it has a long rail. So many options, isn't it great.
Link Posted: 8/25/2004 10:08:37 PM EST
I was just about to post my thoughts, but it appears you figured it out. I have my EOTech on a BM flat top, with the LMT BUIS too. Yours shouldnt tilt at all. Try to tighten it down a little more.
Link Posted: 8/26/2004 4:22:33 PM EST
[Last Edit: 8/26/2004 4:24:35 PM EST by Hateca]
I had the same problem. It appears, depending on whose receiver you mount it on, it will tilt to the left. This is what I did.

I took out my three flattops and put the EO on all three. The Bushmaster was the worst. The Model 1 was better, and the RRA was the best, it was near perfect. (bubble level was used)

There seems to be a slight difference in the machining of the flattop rail +/-. The upper and lower angle cuts appears to vary a few degrees from receiver to receiver.

I don’t know if this is an acceptable tolerance in the receiver, or if it was just bad machining. Anyways I did some swapping of sights receivers and barrels to get the RR receiver where I wanted it.

I think the way the EO mounts, it grabs these angles and it can cause a tilt. If you look at the bottom of the sight, it is flat, but if you look at the left and right V-rails the right rail, that is used to tighten against the flattop, is higher.

Yes, the EO can be zeroed, and most shooters probably didn’t even notice the tilt. (worse on some flattop than others) However, take a look at the sight, you to may notice it. You do not notice the tilt in the Aimpoint because it is a tube and uses a separate mount. You can rotate the Aimpoint in the mount.
Link Posted: 8/26/2004 4:26:47 PM EST

Originally Posted By Mike_Mills:
C4iGrant,

I received the LaRue mount today. There's a problem. It does not fit on the remaining rail space in front of my LMT rear sight. Honestly, it doesn't really fit the EOTech too well, either. The throw lever bangs into the EOTech housing when only partially opened such that the lever cannot be fully opened.

One advantage of the EOTech was supposed to be cost, the Aimpoint requiring an expensive mount in addition to the cost of the sight. If I need this fancy LaRue mount to make the EOTech work (co-witness with the iron sights) the supposed cost advantage is totally lost. Without the mount a performance advantage is lost (can't co-witness).

This is a pain.

As of now, I'm thinking the Aimpoint is winning the battle rather than EOTech. Perhaps you can help me out and allow the EOTech to catch back up.



Yep, I went through all this shit. I don't own any EoTechs anymore.
Link Posted: 8/26/2004 5:43:55 PM EST

Originally Posted By QuietShootr:

Originally Posted By Mike_Mills:
C4iGrant,

I received the LaRue mount today. There's a problem. It does not fit on the remaining rail space in front of my LMT rear sight. Honestly, it doesn't really fit the EOTech too well, either. The throw lever bangs into the EOTech housing when only partially opened such that the lever cannot be fully opened.

One advantage of the EOTech was supposed to be cost, the Aimpoint requiring an expensive mount in addition to the cost of the sight. If I need this fancy LaRue mount to make the EOTech work (co-witness with the iron sights) the supposed cost advantage is totally lost. Without the mount a performance advantage is lost (can't co-witness).

This is a pain.

As of now, I'm thinking the Aimpoint is winning the battle rather than EOTech. Perhaps you can help me out and allow the EOTech to catch back up.



Yep, I went through all this shit. I don't own any EoTechs anymore.



i'm not sure if you've read thru the entire thread yet, but Mike_Mills stated that he only needed to actually adjust the windage and elevation to get it to zero....there was no problem with the sight whatsoever.
Link Posted: 8/26/2004 7:17:36 PM EST
it dosn't matter where the eotech reticle is in relation to the sights it will shoot where the reticle is every time now matter where the reticle is on the sights or in the window.
Link Posted: 8/26/2004 9:57:50 PM EST
[Last Edit: 8/26/2004 9:59:40 PM EST by Mike_Mills]
carbine_kid,

What you said is true but you left out one important condition. It is true AFTER the sight has been zeroed such that point of aim is the same as point of impact. It is this zeroing process that was the problem.

There's no doubt the EOTech mount could be improved. It doesn't sit flat. There's only one spindly screw holding it on.
Link Posted: 8/26/2004 11:51:03 PM EST

Originally Posted By Mike_Mills:
carbine_kid,

What you said is true but you left out one important condition. It is true AFTER the sight has been zeroed such that point of aim is the same as point of impact. It is this zeroing process that was the problem.

There's no doubt the EOTech mount could be improved. It doesn't sit flat. There's only one spindly screw holding it on.



Not ever optical will come out of the box sighted in.
Link Posted: 8/27/2004 2:45:16 AM EST
Ok... While I really like the look of the LaRue mount, will a "plain jane" ARMS #38ex work to raise the unit enough to co-witness the FSB while also providing a built-in folding BUIS and platform to mount the upcoming magnifier?

Thanks.
Link Posted: 8/27/2004 3:21:36 AM EST
Link Posted: 8/27/2004 3:26:25 AM EST
Does the EO-TECH have to mounted so far forward. Will an AA version fit on the back mounting point and not overhang?
Link Posted: 8/27/2004 3:32:35 AM EST

Originally Posted By C4iGrant:

Originally Posted By warriorsociologist:
Ok... While I really like the look of the LaRue mount, will a "plain jane" ARMS #38ex work to raise the unit enough to co-witness the FSB while also providing a built-in folding BUIS and platform to mount the upcoming magnifier?

Thanks.



The #38 raises it to high to co-witness. Besides looking cool, the LaRue Tactical EOTech mount has a lot of functionality (QD, 100% repeat zero, NV mounting platform)...

C4



Interesting... I'm very glad I asked! Thanks!
Link Posted: 8/27/2004 4:12:13 AM EST
Link Posted: 8/27/2004 8:05:48 AM EST
One main benefit of the LaRue mount (my opinion only) is that it makes the EOTech a QD sight. If it fails, you can strip it off and out of the way very quickly. Without the LaRue mount, if it dies, it has to stay in place. If you want to do maintenance, it has to stay in place, etc.
Arrow Left Previous Page
Page / 2
Top Top