Hello

I also purchased an upper from Sherluk and did not notice until I got home, the rear sight is not properly indexed.  To be honest, Im not totally sure what indexed means.  I think I have an idea.

What is the correct position of the elevation knob for a correct index?

How would I go about correcting the index?

How important would it to make sure it was correctly indexed?

Much Appreciated

http://www.ar15.com/forums/topic.html?b=3&f=18&t=328143

I appreciate that link.  I have read that over before posting.

My elevation knob is not set on 8/3 or even close when bottomed out.  It is between 6 and 7 if I am not mistaken.

Apparently someone stupid assemble your rear sight.  Take it to a good AR mechanic.  The rear sight assembly is a pain in the ass to put together.  There's a chance that you have non spec parts in there as well.... this happended to me before.

Ken at S.A.W. was able to spot the aftermarket parts (which I wouldn't have known) and get my weapon right.

Will this work for me to index the rear sight?


In order to adjust your rear sight to the correct setting (A2: 8/3-3, A4: 6/3-6) perform the following:

1) Bottom out the sight. (Turn it down until it won't turn anymore.)

2) Turn it back up until the first 8/3 or 6/3 marking is centered on the tick mark. (If you're already there when bottomed out then skip this step.)

3) Flip the rear sight aperture so that the day time sight (the one with the small hole) is the one that you're looking through when you shoulder the rifle.

4) With a 1/16" hex wrench unscrew the set screw located in the hole on top of the rear sight half way out. (I find it easier to unscrew it half way, all you need to make sure of is that the bottom portion of the rear sight drum is free.)

5) While holding the top portion of the rear sight drum turn the bottom portion of the rear sight drum towards the "up" position of the rear sight. (The following amount of clicks is required for the specific rear sight: 8/3=3 clicks and 6/3=6 clicks in the "upward" direction)

6) Re-tighten the set screw and check you rear sight, it should now have the proper adjustments. If you are one click over or under just repeat the steps. So if you're 7 clicks over then turn the bottom portion of the rear sight drum one click in the "downward" direction of the rear sight.

Yes. Exactly right.

On some rifles, the set screw can be a bit tight the first time you break it loose, so don't get worried if it is. You'll have it setup in no time.

I'd still have it looked at if you care.  My rear sight housing was bad, and I'd never have known.

If the idiot who put it together didn't even get that right, you wonder what parts they used.

I've readjusted quite a few of these, and usually it seems to be easily corrected... meaning no physical problem. I did run into one that had a small burr that was forcing the sight housing slightly backward on the last click as you bottom the sight out. That was easily corrected though.

If he's at least slightly mechanically inclined, I'm sure he'll be fine doing it himself. On the other hand, if he's got ten thumbs and the eyesight of Mr. Magoo... well... not much help for that.

Thank you for the input.  I was able to reindex the rear sight with no problem.  Now, I need to head to the range and resight the gun in.