So . . . I have an AR15 flat top, and my primary sight is an Eotech 512 mounted on it. I'm very happy with it: it is easily zeroed without any particular effort on my part.

But I recently purchased a Burris AR-P.E.P.R. scope mount/rings for it so that I could mount a scope on it (duh . . .).

I love the Burris, it holds my scope well and it fits tightly on my AR. The problem is that the windage of the assembly is way, way off, so I need to use almost all (or all?) of my scope's internal adjustments to bring the rifle to zero.

Is there a way to adjust the mount such that I can move my scope's internal windage adjustment towards its midpoint?

Thanks.

(Cross posted here and at Military & Military Rifles)

Your question is way out of my league. But I'll be watching to read what answers come your way.

get some shims.

Have you tried taking the barrel off & retorqueing it? See if it makes any difference.
Put a bore sight on first & record the settings.

I had the same problem with a set of Burris rings. Oddly enough, reversing the rings solved the problem. It is a shame the PEPR wont allow that...

Any chance your mounting holes are slightly misaligned on either the rifle or the mounts?

Thanks for the responses . . . I really, really appreciate them.

I asked myself if I could solve my problem by moving the mount forward a couple of slots, wondering (as sheephunterab wondered) if that would make a difference (because of eccentric holes or slots).

It was my Great Idea . . . but when I shot 10 rounds, 5 with the mount 2 slots forward of the other 5 rounds, I ended up with 8 rounds in < 1 inch at 100 yards, and the other 2 (pulled) opening the group to 1.75 inches.

I was pissed (because my Great Idea - and Sheephunterab's - had not borne fruit), stunned (because I'm not that good a shot) and gratified (that the rifle is so accurate), all at the same time. (I'm about to enter therapy over this whole sorry affair. . . ).

I've thought a lot about this, and have decided not to use shims . . . I swap my EOTech holographic sight for a scope too often for me to be confident that I could keep track of the shim . . . the last thing I want is to decide to change to scope and find I'd lost the crucial shim).

Given the accuracy of this combination, I think I'll not tinker with it . . . if the worst thing that happens to me is that my scope is at or near its extreme windage setting, I have a pretty good life!

Again, thank you all for thinking about this with me.

I'm a bit surprised you've thrown in the towel on this issue, BL. The cognoscenti say image-movement's tolerance for reticles near the edge is a seductive error that can cause a another form of parallax. If you find a shim that works, you could Araldite it it to the mount to stop it getting lost on removal.

quote:

Originally posted by sambarman338:
I'm a bit surprised you've thrown in the towel on this issue, BL. The cognoscenti say image-movement's tolerance for reticles near the edge is a seductive error that can cause a another form of parallax. If you find a shim that works, you could Araldite it it to the mount to stop it getting lost on removal.

Well, the rig shoots well (sub MOA with two different bullet weights) and I can zero it. I understand that one could introduce parallax by adjusting a scope to near its limits, but as far as I can tell, that hasn't been the case here. So empirically, I seem to be okay.

But I'd be lying if I told you I'm 100% happy. Though I'm satisfied enough for now, I can imagine that at some point in the future I just might give your Araldite solution a try. It's a good idea, and I appreciate it.

I'm facing the age-old dilemma: it works pretty darned well as it is now, so do I want and try to fix it?

I'm a big fan of epoxy resin in home gunsmithing. As well as using it for bedding, I've glued on fore sights and removed the first stage from military triggers by sticking bits of hacksaw blade across the gap in the sear arm.

The 5-minute or clear versions would probably do for the shim purpose because you don't have to heat it as much if you want to get it off again.

quote:

Originally posted by sambarman338:
I'm a big fan of epoxy resin in home gunsmithing. As well as using it for bedding, I've glued on fore sights and removed the first stage from military triggers by sticking bits of hacksaw blade across the gap in the sear arm.

The 5-minute or clear versions would probably do for the shim purpose because you don't have to heat it as much if you want to get it off again.

Thanks for the advice. I'm always open to learning, and I value the advice of people more experienced than I.

If I decide to do this, I'd probably go "all-expensive" and cut up feeler gauges rather than hacksaw blades. Just because . . . I'm anal compulsive (or as, in the day, when a fellow student quipped "anal expulsive" ).

Yeah, feeler gauges are good, though the one you finish up using might be thicker than a hacksaw blade. A lamination of thin feeler-gauge pieces would be more flexible if needed on a curved surface. The Araldite does take up some space, of course, as I found when fitting a loose barrel-band front sight to my sporterised MS the other day.

I use circular feeler-gauge bits behind cartridges for determining headspace, but I guess that trick is well known.