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3/13/2003 4:40:06 PM EDT
zeroed with small aperture today at 50 yds.when i changed to the large one,the zero moved 2 ins. left and 2 ins. down. this normal?
3/13/2003 6:10:54 PM EDT
[#1]
Yes,
the two apertures are not on the same plain/height.

Large is a battle sight for short ranges, the small for long ranges.
3/13/2003 6:17:29 PM EDT
[#2]
what about the windage change? 2 in. at 50 yds seems like a lot
3/13/2003 8:17:10 PM EDT
[#3]
The apertures could be drilled off of center line with each other.
3/15/2003 3:48:32 PM EDT
[#4]
Oddly enough, I am having the same problem with windage.  The rear sight is indeed a Bushmaster, so I doubt it is off-center, altho it is possible.  Any other suggestions, while I figure out how to measure the apertures?  Ops
3/15/2003 4:14:24 PM EDT
[#5]
The rear sight has 36 threads per inch.  
The sight radius on a 16" barrel is 14.75".
Rotating the sight 1/4 turn will move point of impact by 1.7" at 100 yards
(1.25" with a 20" barrel)
changing from large to small hole will shift the point of impact to the right.

You should zero the rifle with the small apperature.
3/15/2003 4:31:27 PM EDT
[#6]
zeroed at 50 yds. with small----turn up large and zero changes 2in. left at 50---is this not a lot?
i have a 20 in. barrel
3/15/2003 4:50:03 PM EDT
[#7]
The sight is on backwards
3/15/2003 4:53:04 PM EDT
[#8]
sight is not backwards
3/15/2003 5:59:49 PM EDT
[#9]
About 3 times too much. Try a new rear sight aperature, they don't cost much.

The aperatures being offset by about .01" would explain your problem.

If you have calipers measure the distance from the side to the hole.

I would be interested in what you find.
3/16/2003 6:30:10 PM EDT
[#10]
Measured, and the smaller aperture was about .003" too far to the left.  I corrected it with a Swiss needle file, will test fire and report.  ops  
Edited to add:  Zero for windage is now dead center for both apertures.  There is apparently about 3 MOA difference in elevation, which works for a 100 to 300 yard zero.  Ops
3/20/2003 1:26:49 PM EDT
[#11]
The two sight apertures are supposed to be offset by the amount of movement caused by the quarter turn when you flip from one aperture to the other.  They should NOT cause a windage change.  There SHOULD be an elevation change when going from the 0-200 (large) to the 300 (small) aperture.

Your fix, with the needle file, was the correct one.  Apparently your rear sight blade was not correctly made.
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