Warning

 

Close
Confirm Action

Are you sure you wish to do this?

Cancel Confirm
AR15.COM
AR Sponsor
6/11/2004 9:36:12 AM EDT
Hello All,

I have been reading here for a while now and decided to take the plunge and ask for some help!  I have searched on google and the forums and can't find any answers to my problem so here goes...

I recently mounted my Eotech 512 rev.f sight to a bushmaster flat top upper.  I am using the large thumbscrew.  All is good except the sight is canted noticeably to the left.  It's pretty clear that it cants to the side with the screw and that the short "rail" on the opposite side makes far less contact with the picatinny cutouts than the thumbscrew side does.  How do any of you deal with this?  I don't want to shim it or anything like that since it seems like the wrong way to do things.  Am I doing something wrong?

Any help is greatly appreciated as the cant causes me some trouble when first shouldering the rifle.  The reticle appears to be about 4mm to the left of the front sight post with a good cheek weld.
6/11/2004 9:53:47 AM EDT
[#1]
It should be sitting flat.  If not, then something is wrong.  Can you post a pic?
6/11/2004 9:55:20 AM EDT
[#2]
Is it resting on the delta ring? Have any pics?
6/11/2004 10:06:05 AM EDT
[#3]
I will take some pics when I get home tonight and post them here.  I thought it might be making contact with the delta ring last night so I remounted it dead center on the rail and still the same leftward cant.

If you turn the rifle upside down and look at the bottom of the optic/rail you can clearly see that there is more of the rail showing on the right side than on the left.  If you loosen the nut the sight will sit flat but as soon as it snugs all the way down....

 Thanks for the quick responses, this site/forum is truly one of the few good communities on the net.
6/11/2004 11:23:46 AM EDT
[#4]
Sounds like your upper's rail may be out of spec. Do you have access to another upper receiver or section of rail? Do you have a railed handguard you could try mounting the EOTech to, to see if the problem follows? Did you over torque the screw when first installing the EOTech? It only takes tightening by hand and then about a 1/4 to 1/2 turn more with a coin to tighten.
6/11/2004 11:25:27 AM EDT
[#5]
I will look at mine tonight and get back with you.

Is the thumbscrew after market ?
6/11/2004 11:38:11 AM EDT
[#6]
Quib,

I do not have another flat top but I have an A2 upper with an ARMS carry handle rail on it.  I will try that.  I thought the rail might be screwy but both my BUIS sit on it perfectly level if I mount them forward where the 512 is.  As for over tightening, finger tight only, didn't even use a coin.  Also, it is the factory large thumb screw that comes in the box with the unit.

Thanks for checking yours for me baddog, let me know if you notice anything.

Thanks again for the help guys.
6/11/2004 12:26:11 PM EDT
[#7]
I've seen this when I had my Fobus M44 and the EO Tech was hitting them.  If you're using the M44s you have to grind off part of that 'ring' at the end to allow the EO Tech to hang over the handguards.
6/11/2004 1:44:03 PM EDT
[#8]

Quoted:
I've seen this when I had my Fobus M44 and the EO Tech was hitting them.  If you're using the M44s you have to grind off part of that 'ring' at the end to allow the EO Tech to hang over the handguards.



Good point. Can you post a pick of your weapon or list any accessories you have mounted that may effect the mounting of the EOTech?

Like I said, try it on another rail. Even the A2 rail you have on your other rifle is ok, it will at least let you know if the problem is with your optic or the A3 uppers rail.
6/11/2004 2:00:49 PM EDT
[#9]
maybe you unscrewed it to much and the hinge fell out and you put it back wrong
6/11/2004 2:08:14 PM EDT
[#10]
Awesome help and responses guys!  I will be checking all of your suggestions and posting pics tonight!
6/11/2004 4:18:35 PM EDT
[#11]
Ok, haven't got any pics yet, but I put the eotech on my A2 upper with ARMS mount and it is canted left there also.  There appears to be a problem with the sight body itself.
6/11/2004 6:38:10 PM EDT
[#12]

Quoted:
maybe you unscrewed it to much and the hinge fell out and you put it back wrong



Drew-tx may be onto something. Try unscrewing the clamp portion and fliping it upside down, hell it's worth a try!
6/11/2004 6:54:03 PM EDT
[#13]
Absolutely, doing that now!
6/11/2004 7:02:54 PM EDT
[#14]
Nope, the clamping components check out just fine.  I have access to all manner of optics, I will try some ACOG's and Aimpoints tomorrow.  My guess is the first one I mount will be true.

I can't say enough about how friendly and helpful AR15.COM members are!  I half expected to get flamed but I can see that I chose the right place to park my insatiable appetite for all things AR..
6/11/2004 7:05:36 PM EDT
[#15]

Quoted:
Nope, the clamping components check out just fine.  I have access to all manner of optics, I will try some ACOG's and Aimpoints tomorrow.  My guess is the first one I mount will be true.

I can't say enough about how friendly and helpful AR15.COM members are!  I half expected to get flamed but I can see that I chose the right place to park my insatiable appetite for all things AR..




If in fact there is something wrong with it, notify EOTech soonest and they will take care of it!


C4
6/11/2004 7:26:31 PM EDT
[#16]
Will do!
6/22/2004 2:53:03 PM EDT
[#17]
Just an update....  It turns out (duh) that the front sight assembly/barrel is canted!  They were a little skeptical of my claim until I told them that I am not blind and that you can actually look down the muzzle and see the cant without even bothering with sight lineup.  I was surprised that they did not offer to pay for the shipping costs since they sent me an obviously mis-assembled (probably not a word but a good description) upper.
AR Sponsor