AR15, A2 NM rear sight questions


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HSMITH
March 19, 2005, 11:30 AM
I would like some advise, as I am just getting into AR's. I have bought all the parts and assembled a rifle, the A2 upper was completely assembled when I got it with A2 NM rear and what appears to be an A1 NM front. The rear sight sits on the upper at a little bit of an angle, but that isn't what is bugging me the most. The sight has about 140 clicks of windage travel, when centered the hash mark on the peep is about 12 minutes right of the center mark on the sight base. Is this normal? Is there anything I can do about it? How about getting the sight to sit squarely on the upper?


Initial setup of the sight is one turn up from bottomed on the front sight, and 3.5 minutes up on the rear with windage centered. Sound right? I hope to shoot it tomorrow.

Any help is appreciated. Thanks.

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lycanthrope
March 19, 2005, 06:44 PM
It's not uncommon. To get the rear sight to sit evenly you need to pin it.

These guys might do it: www.whiteoakprecision.com

Steve Smith
March 20, 2005, 04:34 PM
The rear sight should twist against the left side of the charging handle. If you want to get rid of it you have to have the rear sight pinned. I would suggest that you not worry about this at all. All of my match guns have pinned rear sights, but I don't think you have to worry about this yet. Since the axis of twist is almost directly under the aperture anyway, the twist has very little affect on the position of the sights. Now, about your windage issue. I take it you ran the sight from one side to the other and counted and then divided by half. That would be your Mechanical Windage Zero. I would suggest shooting the rifle from that position and see where it prints. You say that there is 12 MINUTES between MWZ and the hash marks?!! That's an awful lot. If you have 1/2 minute windage that is 24 clicks, or if you have 1/4 that is 48 clicks which is well over HALF of your total windage to one side of the sights (MWZ vice hash marks) which makes no sense. Perhaps you have 12 CLICKS from hash mark to MWZ? That would be 6 or 3 minutes depending on your sights and though still too much, it is more acceptable than 12 minutes. Get bacjk with me but ultimately you will just have to shoot it and find out what is true, the hash mark or the MWZ...let's hope it's the MWZ because you will still have 70 clicks each way to run the sight.

RE: your elevation. I believe that is fine if you are set up for 200 yards. If that was for 100 you are set too high. Run the front sight up one rev and re-zero the rear (more than likely you will come up 1.5 minutes from the bottom). Ensure that the tall side of the front sight is facing the rear sight and turn it in complete revolutions.

HSMITH
March 21, 2005, 10:03 AM
Thanks for the insight guys.

Steve, I was hoping you saw this and had time to reply. I shot it yesterday.

Some assumptions I have made: NM sights are 1/4 minute for windage and elevation. I have an A1 front sight, 5 position detent on a round post front sight. Is this correct?

For clarification, mechanical windage zero was figured by counting every click and coming back to center, half the clicks back.

I shot the gun yesterday. I was up 14 clicks from MZ on the rear , and mechanically centered on the rear, front sight was one full turn up from bottomed since I had read that is a good starting position for all components. I ended up dead center for windage and 3/8" low at 25 yards (as I have read I should be) with the front sight one detent above being bottomed out, the same 14 clicks of elevation from MZ, and back 24 clicks left.

I shot it at 100 with the same sight settings, dead on or about as close as I can get. I was getting 2" groups but cleaning every couple shots for barrel break-in etc and shooting targets poorly suited to the sights. At 200 yards it was dead on also, with the small aperture it was about an inch and a half high at 200. It was quite cold but almost no wind, ammo was WWB 55 grain FMJ.

The hashmarks are nearly lined up now, but I only have another 46 clicks left and 94 right. I am thinking it ought to be closer than that.....

Was I correct in leaving the rear up 14 clicks and getting the elevation corrected by adjusting the front sight?

I am happy with the way it shoots, there were some small snow piles on the berm behind the 200 yard line that were 4-8" in diameter and 210-225 yards out. I was able to hit them easily. I am just not sure the rear sight is set up correcly.

Thanks again for any insight anyone can provide.

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