My fixed BUIS's are zeroed through my Aimpoint M2.

I've only had the Aimpoint for a few months and today was the first time I tried to shoot the BUIS's with the Aimpoint removed.  It seemed that the groups went high and right about 1.5" from POA.

I know that this is too be expected as you're putting glass between the sights.

What changes do you see in your zero when you remove the optic?  What happens to the POI?

Are there differences between Aimpoint and Eotech in terms of how the POI shifts?

Do you zero through the optic (for true cowitness -- my current choice) or with the optic removed?

Just curious if everyone else is getting the same shift in POI than I am, or are seeing something different.

EDITED to add that I use the 50/200 IBZO and was shooting from 50 yards today.

suggested reading:

[url]http://groups.msn.com/THeMarylandAR15ShootersSite/zeroingmethods.msnw[/url]

I zero w/ out the optic, attach the optic and zero it, then turn it off and see where the irons hit.  I never adjust them again, but the iron POI may shift 2-3" at 50 yds.  

This does not concern me, as if I am in the unlikely situation where my battery is dead or I forget to turn on the Aimpoint and I need to shoot, the target is most likely so close or so large it will not matter.  If the AImpoint goes dead in the field or at the range, I simply remove it and shoot w/ irons, which are correctly zeroed.

I am sure ther are other ways to do it, but that's my method, fwiw.

Lumpy:

Thanks.  Yeah, actually I've been over that (numerous times[:)]).  Maybe my original post wasn't all that clear.  Actually, I admit that I was rambling.  [:D]

Initially, I just stuck my Aimpoint on, zeroed it, and then adjusted my fixed BUIS's to the Aimpoint dot.  (My fixed BUIS's is a chopped carry handle.)

Recently I upgraded my BUIS with an Ashley (now XS) same plane rear aperture.  I always knew that the BUIS's have a different POI with and without the Aimpoint in place, but never knew what the difference was.

Today I zeroed my BUIS's first without the Aimpoint mounted.  Then installed the Aimpoint and shot my BUIS's again.

I guess my specifically I was wondering if all Aimpoints distort the POI up and to the right.  I would suspect that this would have something to do with the design of the glass in the optic.

Is there a pattern to Aimpoint POI distortion?

What about Eotech?

The MD AR15 site linked above indicates a 5" low POI shift through a Reflex.  Is this consistent with all Reflex's, or is there some variance for individual eye perception?

Just trying to understand more about the particular POI shift in Aimpoints so I can decide how to best deal with it in my setup.

Unfortunately, I wasn't able to spend enough time today at the range to really study this to any degree.  I was only able to fire a 2-3 groups to check the POI shift.  I was so rushed to get off the range (we were zeroing at 50 yard on a 100 yard range, and others were waiting to use the range -- all targets must be at the backstop) that I'll want to go back and carefully keep track of what happens over multiple groups.

Any info I can get on this before I go back will be helpful.

TIA.

I think a lot of it has to do w/ individual eyesight, corrective lenses, etc.  The shift through y Reflex II was hardly noticeable, nowhere near 5".

Through my Aimpoint, I hit 2-3" low with the irons, OK for windage.