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Page AR-15 » AR Discussions
AR Sponsor: bravocompany
Posted: 5/9/2003 12:21:06 PM EDT
Sorry if this is a stupid question, but with the IBZ, should I always leave the dial to the -2 mark, i.e. is this my new bottomed out setting?  The reason I ask is that in the IBZ page, it says that for patroling, set the flip up sight to the large aperature, and turn the dial down to 300/600.  Is the point of impact for the two flip up sights the same, one just has a larger aperature.

I was shooting and zeroed the rifle at -2 with the smaller (unmarked) aperature, but when I switched to the larger aperature both at -2 and at 300/600, the rifle shot low.  Could someone please clear this up a little

Link Posted: 5/9/2003 2:41:52 PM EDT
The big aperture is offset to shoot approximately 2 MOA lower than the small aperture.  The IBZ is zero at 50 yds with the dial at 8/3-2 and small aperture.  If you flip to the big aperture you need to move the dial up 2 clicks to 8/3 to compensate for the offset.

Since you say "300/600" you must have a detachable carry handle.  Remember that the detachable handle is "half-clicks" (6 clicks between 3 and 4 vs 3 clicks on an A2) so 8/3-2 is really 6/3-4.  

If you don't like having to move the dial when you switch apertures, Ashley makes one without the offset.  Problem is that both apertures are larger than their counterpart on the A2 sight.
Link Posted: 5/9/2003 6:37:59 PM EDT
Thanks for the response, but wouldn't moving the dial back to 300/600 actually lower the point of impact more?  It seems to me as you dial UP, then the point of impact moves up, but since we at at -2 with small, the the large shoots lower, moving from -2 to 300/600 would lower the impact even more
Link Posted: 5/12/2003 6:51:34 AM EDT
6/3 is higher than 6/3-2.  At 6/3-2 it should be all the way down.  6/3 is 2 clicks UP, then once around the dial and you're back at 6/3 but with the sight much higher.

From the factory most sights will bottom out right at 8/3 or 6/3, which is why you have to adjust the sight wheel as described in the IBZ.  (The numbers are read from the left side of the rifle.)
Link Posted: 5/12/2003 8:05:16 AM EDT
The A2 apertures were orginally designed so when the small apertured was zeroed for 300M the larger aperture would have a 200M zero.

So you need to set the dial to '3' when using the larger aperture.

There is another issue though.  The makers of the Ashley Same Plane found there is a variance among the rear sights and it could MUCH bigger than its supposed to be (there is a FAQ on it on their website).  If your large aperture is hitting low @ 50y (after doing the IBSZ) then you probably have one of those 'problem child' apertures.  You have two solutions - click up (past 8/3) till you find when YOUR large aperture ZEROs at 50 yards (and remember that setting - as the elevation wheel is calibrated for the small aperture); or you get a Same Plane rear aperture.

Personally I like the Ashley (now XO) Same Plane Rear Aperture as it solves the problem. Yeah the holes are bigger (bummer) but its not like we're trying to shoot X-rings.
Link Posted: 5/12/2003 10:24:54 AM EDT
now XS. formerly AO. [;)]

they rock.
Page AR-15 » AR Discussions
AR Sponsor: bravocompany
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