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9/22/2017 12:11:25 AM
Posted: 1/12/2006 11:01:24 AM EDT
Does anyone know the offset between the 2 apertures on the A2 sight? I was looking for how much lower the 0-2 sits than the smaller hole.

T
Link Posted: 1/12/2006 11:13:24 AM EDT
[Last Edit: 1/12/2006 11:14:10 AM EDT by EternalVigilance]

Originally Posted By bfett:
Does anyone know the offset between the 2 apertures on the A2 sight? I was looking for how much lower the 0-2 sits than the smaller hole.

T




What pisses me off is that for some reason I always shoot low and left with the large apeture. With the small apeture I am dead on. I haven't been able to figure it out.

I use the IBZ (50 yard). I go four clicks below for my small apeture, and right on the 6/3 for the large apeture. 16 inch carbine.

Any help?



Maybe I should just play with it and find out where I should really be putting it for the large apeture. You would think following the instructions would work though.


http://groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw
Link Posted: 1/12/2006 12:27:07 PM EDT
EV
What you are saying makes perfect sense, the large aperture is lower than the small (by the numbers below) so you should be hitting lower with the large aperture. Also if you are adjusting by 4 clicks with a carry handle (usually 1/2MOA/click) then you probably have iteration 1 as it creates approx. a 2.5MOA shift.

Now I have no idea why you are hitting left (tolerances maybe) hewww.xssights.com. For anyone else interested it appears there have been 3 different types..

1st iteration was .014" offset creating a 2.52" change in POI at 100yrds.
2nd iteration was .017" offset creating a 3.06" change in POI at 100yrds.
3rd iteration is 0.24" offset creating a 4.36 change in POI at 100yrds.

T
Link Posted: 1/12/2006 12:40:21 PM EDT

Originally Posted By bfett:
EV
What you are saying makes perfect sense, the large aperture is lower than the small (by the numbers below) so you should be hitting lower with the large aperture. Also if you are adjusting by 4 clicks with a carry handle (usually 1/2MOA/click) then you probably have iteration 1 as it creates approx. a 2.5MOA shift.

Now I have no idea why you are hitting left (tolerances maybe)

I did find the info BTW (in a FAQ on www.xssights.com. For anyone else interested it appears there have been 3 different types..

1st iteration was .014" offset creating a 2.52" change in POI at 100yrds.
2nd iteration was .017" offset creating a 3.06" change in POI at 100yrds.
3rd iteration is 0.24" offset creating a 4.36 change in POI at 100yrds.

T




Thanks for the info. I also found this on the faq:


All of the points of impact shifts shown above are for the standard barrel AR-15/M-16 that has a sight radius of 20 inches. The shorter sight radius (14.5 inches) of the M4 carbine and weapons of similar configuration increase the amount of point of impact shift. The shifts for these shorter sight radius weapons are 3.48, 4.25, 5.96 inches respectively.



I am actually still hitting very low AFTER I do the adjustment of four clicks. Normally they say to do two clicks but since I have a 6/3 sight (removable carrying handle) you are supposed to do four clicks. If the shift at 100 yards can be up to 5.96 inches then I guess that explains why I am still hitting low. What this means unfortunately is that even if I figure out how many clicks I really need to go, say up to six or seven clicks (which would be two or three clicks past the 6/3), then the whole range adjustment on the wheel is fucked up and the whole purpose of adjusting your wheel for the IBZ so that the ranges are still correct on the wheel while allowing you to use the flatter 50 yard zero is FUBAR.

Maybe if I can figure out the number of clicks difference, then I can just readjust my wheel again so that instead of going four clicks below 6/3 for the small apeture, I am going the number of clicks difference needed to compensate for the difference between the two apetures.

FUCK! Might as well buy an aimpoint! Be a hell of a lot easier! What a PITA!

Well, at least now I might be able to start using the large apeture. I always just use the small one.

Link Posted: 1/12/2006 12:43:43 PM EDT
New and interesting question.



Perhaps the GI zero isn't as bad as we all thought. I wonder if the difference between the two apetures is supposed to automatically compensate for bullet drop out past 200 yards. As you increase in range after that you adjust the wheel, but the adjustments on the wheel are taking into account the fact that out past 200 yards you are supposed to be using the large apeture?

Link Posted: 1/12/2006 12:50:53 PM EDT
[Last Edit: 1/12/2006 12:51:47 PM EDT by bfett]

Originally Posted By EternalVigilance:
New and interesting question.



Perhaps the GI zero isn't as bad as we all thought. I wonder if the difference between the two apetures is supposed to automatically compensate for bullet drop out past 200 yards. As you increase in range after that you adjust the wheel, but the adjustments on the wheel are taking into account the fact that out past 200 yards you are supposed to be using the large apeture?




That is almostcorrect... the small aperture is used from 300 to 800 meters (or 600 in your case) using the BDC. The large automatically readjusts you to a new zero, so the BDC does not aplly with the large aperture (so you should always be on 6/3 when using it). Basically according to my ballistics calculator the 3 iterations of A2 apertures reset your zero to 200m for the first iteration, 180m for the second and 130m for 3rd approximately...

T
Link Posted: 1/12/2006 1:03:45 PM EDT
Maybe you want to get a same plane aperture.

T
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