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Veracity
03-12-11, 11:18
Guys,

I'm looking to fix or trouble shoot a bit of a problem I'm having with an A2 rear sight. The elevation knob will not rotate much past the 4 mark. Then, it stops cold.

This isn't my "go to" rifle, so I don't mind tearing it down for a while.

Have you guys disassembled any A2 rear sights? That, and a barrel swap are the only things I haven't done yet.

Is it a horror show? Impossible to reassemble? Lots of swearing and blood?
AMMOTECH
03-12-11, 11:33
I'd try to flush it with a spray cleaner and then re-lube it and see if that helps before I'd start to take it apart.
If you do decide to brake it down then do so inside a shoe box or tub to catch the small parts. (ball, spring).

http://www.parts4ar15.com/images/parts/A2-Upper2.jpg


Take a look at this vid before you start.

http://www.brownells.com/.aspx/lid=11435/learn/

.
Amicus
03-12-11, 11:45
What is the lowest setting it can go to? If the wheel turns well past 2-3 clicks below the lowest range setting, then it may be improperly calibrated. Just how far the lowest range and click settings are depends on whether the A2 sight is for rifles or carbines, and whether it is arranged for half clicks or whole clicks.

Alternative procedure: if the rear aperture appears to have "topped out" when you turn it past "4", then it is possible that it was improperly calibrated at the factory. Best way to visually see if the sight has topped out is to another A2 sight, but this is not precise.

If it is a calibration problem, the fix involves a 1/16" hex wrench and about 5 minutes.

If all this sounds like gibberish (I'm in a hurry), read Santose' excellent article on improved battlesight zero at:

http://sixty-six.org/x_drive/improved_battle_sight_zero.pdf

Look at p. 3, #1. That should give you an idea about where the sight should be from the factory (whether you have a /8 or 3/6 sight, and whether it has half-clicks). If you can continue to turn the sight downward beyond the points he has outlined, it is probably miscalibrated and needs to be corrected. The IBZ instructions should give you an idea of how to do that.
Surf
03-12-11, 14:00
Does the rear sight housing actually look like it is bottomed out at 4? If it is as mentioned by Amicus it may simply need to be aligned correctly. If not, something might be causing an issue.

If you attempt to take it apart, doing the rear sights on an A2 style is the most frustrating part of the entire rifle. Not saying it is hard if you do it a lot, but if you haven't done it before and I am pretty sure you haven't, do things slow and deliberate. Losing a spring or a ball bearing will ruin your day.

On my A2 sights I also adjust the sights and use a IBZ 50 yard zero and use the 6/3 or 8/3 for 300.
Veracity
03-12-11, 19:30
Thanks guys.

I'll get on it tomorrow.
Amicus
03-12-11, 22:30
If all this sounds like gibberish (I'm in a hurry), read Santose' excellent article on improved battlesight zero at:

http://sixty-six.org/x_drive/improved_battle_sight_zero.pdf

Look at p. 3, #1. That should give you an idea about where the sight should be from the factory (whether you have a /8 or 3/6 sight, and whether it has half-clicks). If you can continue to turn the sight downward beyond the points he has outlined, it is probably miscalibrated and needs to be corrected. The IBZ instructions should give you an idea of how to do that.

Sorry, small goof here. The position indicated is where the sight position after recalibration for the IBZ. According to Santose, the sight should bottom out at the 8/3 (or 6/3, as appropriate) position from the factory. If yours does not -- if it bottoms out below that setting (if I am reading your complaint correctly), then you may have a calibration problem. Solve using Santose instructions.

Let us know how this works out, please.
Veracity
03-13-11, 20:24
I printed up the Santose stuff....just like I did a couple of years back...and I did the proceedure.

It seems to be set properly as far as the BSZ stuf goes, but the elevation wheel will not rotate past 4.
Amicus
03-14-11, 08:15
I printed up the Santose stuff....just like I did a couple of years back...and I did the proceedure.

It seems to be set properly as far as the BSZ stuf goes, but the elevation wheel will not rotate past 4.

It appears that you may have a mechanical problem within the sight, and that is way beyond my ken to troubleshoot without looking at it. Good luck.
nimdabew
03-14-11, 14:19
It appears that you may have a mechanical problem within the sight, and that is way beyond my ken to troubleshoot without looking at it. Good luck.

Translation: Yup, it's ****ed.