EOtech zero loss when detached

[richrock]

I recently had my Eotech AND rails off to move my foregrip up a bit. I use the VTAC EXTREME BattleRail - By Troy Industries http://www.vikingtactics.com/handguard.html so the railed sections other than the top rail have to be pretty carefully thought out ahead of time to same some difficultly later. Anyway, I could have sworn that I put the EOtech back on exactly where it had been.

Went to shoot today, and was off by like 2-3 feet at 50 yards? High and right. Finally got on paper, but I'll have to get back shortly to bring it closer to an acceptable zero. Prior to removing my handgaurds it was dead for my purposes, and held this zero for several range trips before I made my foregrip rail move.

What gives?? Maybe I missed the rail when I put the EOtech back on, but I'm 99% sure it's in the same spot it's always been. Handgaurd is right back the way it was, possibly more tightly screwed together, but I don't think that would matter. Even if I moved the EOtech front or back a notch or 2 I wouldn't expect 2-3 feet worth of missed target.

And yeah, I read up on the EOtech fake stuff and am reasonably certain mine is not a clone. User error? Mystery? Normal and something I don't know about? Correct me if I'm wrong but can't you pop the EOtech on and off all day without losing zero?

Set me straight please!

[NoMoreOp4]

If I understand your post correctly, you actually took the rails entirely off the gun? If so, I would say that would cause a lot more issues with the zero being off that possibly putting the sight on a different rail than it was on previously.

I take my acog off all the time and when I put it back on, its never more than 1" or 2" off of zero.

EDIT:

Zero it again, take off the EOtech only, and then put it on and shoot again and see if the same thing happens.

[red dog]

i,m thinking your problem is with the removal of the rails themselves, probably not back in the same as original set up. keep in mind you can,t remove any type of sight system and reinstall and maintain absolute zero. with eotech and other simular systems it is actceptable to be off 1 or 2 moa. picture if you will a very slight difference on your reinstall, what that translates to at 100yds. it,s a wonder they reinstall as well as they do.

[richrock]

I did take the handguard rail system off entirely. My site bridges the railed flat top upper And the railed handgaurds. It seems to me that they fit together tightly and really only in one way at least to me. Maybe there is some play in how it goes back on what do I know. I guess I could believe how a fraction of a fraction an inch causing a missed zero. Its the extreme miss of 3 feet that has me frustrated and perplexed. Im damn sure not taking my rails off anytime soon again, and maybe not even the eotech just to be safe. I'll probably be 150 rounds to re-zero.

[Tomcat088]

I did take the handguard rail system off entirely. My site bridges the railed flat top upper And the railed handgaurds. It seems to me that they fit together tightly and really only in one way at least to me. Maybe there is some play in how it goes back on what do I know. I guess I could believe how a fraction of a fraction an inch causing a missed zero. Its the extreme miss of 3 feet that has me frustrated and perplexed. Im damn sure not taking my rails off anytime soon again, and maybe not even the eotech just to be safe. I'll probably be 150 rounds to re-zero.

Fractions of inches definitely add up, especially as range increases. Even 1mm or 2 can make a difference at even 100 yards. Most people would be surprised at how great of a difference just a little fraction of an inch can make. If you carry that fraction of an inch out further on the same angle, it's quite a lot. I'm also guessing that the change in zero is because you removed the rails. I'm curious though, why so many rounds to re-zero? I'm not trying to be a jerk, but just wondering how you're sighting in that it takes so many.

[red dog]

do yourself a favor , pick up a site lite laser bore sighter. they are reasonably affordable, depending on model. they come with a web site that you set up with all the varibles such as sight height, caliber, bullet weight, bullet coefient, ect. then it prints you a target. the target has a point for the laser beam and a point for the cross hairs or in your instance the dot. i,ve used one for a year now and my customers are surprised at the results i give them. some don,t even have to fine tune their weapons, others are within a inch. saves ammo for the important things not to mention it can pay for itself in the long run. happy shooting, red dog

[richrock]

I'm curious though, why so many rounds to re-zero? I'm not trying to be a jerk, but just wondering how you're sighting in that it takes so many.

fortunately so far I'm exaggerating, and hopefully it doesn't take me 150 rounds to get zero. PLEASE feel free to amend my method, but this is how I went about it yesterday:

walked out to about 15 yards, fired 2 rounds and noted location.
25 yards, 2-3 more rounds noted location and adjusted a few clicks. at this point i was high and right maybe 6" if I recall (rough night and awfully foggy this AM)
Adjusted a couple clicks and got little improvement with follow up 2 or 3 shots.

At that point I returned to 50 yard line knowing I've gotta come down and left a good bit. My mistake was in guessing at how much the 6" miss at 25 yards exponentially grows at 50 yards, so my 1/4 MOA adjustments took me forever when at back at the 50 line to just get back on paper. It was 18"-24" high and right when I had to call it a day.


My range only allows 10 rounds fired from "open ground" and uncovered by the range shelter. Neighbors complain...don't get me started...why buy a house next to a firing range?...anyway...

do yourself a favor , pick up a site lite laser bore sighter. they are reasonably affordable, depending on model.

got myself a bore sighter, but accidently left it on and the battery drained quickly. i didn't anticipate needing it yesterday so never changed the battery. somewhat expensive lesson. what's that phrase about always being prepared??? nonsense.

[kindred_spirits]

What model EoTech is it?

If it uses the standard thumbscrew rail mount, those mounts are not designed to return to zero. If you want to have a true RTZ setup, mount the EoTech to a LaRue LT-110 riser. This will also raise the EoTech to a 1/3 co-witness.

It's also generally not a good idea to "bridge the gap" between the reciever and rail when mounting optics.

[richrock]

What model EoTech is it?

If it uses the standard thumbscrew rail mount, those mounts are not designed to return to zero. If you want to have a true RTZ setup, mount the EoTech to a LaRue LT-110 riser. This will also raise the EoTech to a 1/3 co-witness.

It's also generally not a good idea to "bridge the gap" between the reciever and rail when mounting optics.

It's a 512, AA battery style. I'll look into that LaRue riser.

I have it mounted so the rear of the EoTech leaves the T-11 mark on the upper receiver rail as the last visible spot, then the battery compartment sticks out onto the railed hand guards. I do it this way because I have a quick detach magnifier that needs the real estate between my flip up rear and the EoTech.

I tend to favor the "scout" set up for an EoTech, but don't like it much farther forward than it is now. Maybe I can muster the balls to try moving it forward some more so it's entirely on the hand guard rail or see if I can come up with something to move it back entirely on the receiver without giving up on my magnifier. OR save some money and begin being able to justify buying an ACOG.

I think I know the answer, but why is it a bad idea to "bridge the gap"?

[IronButt]

I have an EOTech mounted on a LaRue QD that I move between guns frequently & it's never lost zero. Either your rails got moved slightly when you reattached them, or maybe you torqued the EOTech down differently when you remounted it.