Posted: 1/31/2016 10:56:35 AM EDT
| I just bought a new Armalite N.M AR15. My first attempt to zero it in wasn't the greatest experience. I was shooting very high out of the box at 100 yards (not even on the paper.) So I moved in to 25 yards and made my sight adjustments. I didn't realize that the Armalite front N.M sight is tapered and that the wide part of the sight needs to face the shooter. So basically it needs to me moved up or down in complete revolutions. Well I didn't do that and I think it resulted in making the front sight post canted to one side. As a result to get a 100 yard zero my rear sight had to be cranked WAY over to the right. I called the shop that sold me the rifle and they said to readjust the front sight so the wide part faced me, and to re center the rear sight. My range only has a berm out to 200 yards, so I think I want to try the 50/200 yard zero. My question is, where should I set my rear sight elevation to get started at 50 yards. Out of the box I think it was around 5. When I was shooting at 100 yards I think I had it cranked down to 1. Sorry for the long post, but I want my second attempt to zero in this great rifle to be better than my first. |
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Does it have a set-screw or clamp-on style front sight? If so, set the rear sight to mechanical zero. Separate the upper and lower, remove the BCG, rest the upper on bags or in a vice, and boresight and adjust the front sight's windage to match, then lock it down. My original front sight post's base (the part with detents) was about flush or just below flush with the deck. Perhaps start around there with the proper orientation and move up or down in whole revolutions until it boresights close, then fine tune with the rear sight. I like my 100 yard zero about 3 MOA above bottom. ETA: even with a pinned front sight, starting with mechanical zero is a good idea. |
FBHO
Teener Krew 4 Lyfe
Thank you, Jeff. #24ever
Teener Krew 4 Lyfe
Thank you, Jeff. #24ever
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competitors have different eyes, and as the national matches seem to be mostly under 18 or over 60 yrs old, there is a big selection in front sight posts that are CMP/HP legal that help people of different ages focus on the thing. size seems to make a big difference.
one of many examples of quality retailers: http://www.whiteoakarmament.com/xcart/home.php?cat=287&sort=orderby&sort_direction=0&page=2 you can get a front sight post here that is .040 .045 .052 .062 .072 or standard width. they are $10. for that price, you might want to try a different one. your choice of zero will depend entirely on what type of target you shoot. if you are shooting the standard national match bulls eyes, then you can do a center hold, 6 oclock hold, line of white, flat tire, reverse flat tire, etc. as far as distance, just about everyone uses a 100 yard zero. if you're shooting some other type of target or a wide range of targets, e.g. plinking, then it gets a little more complicated. 6 oclock gives you the best view of the target, but isn't very precise since you have no idea how big your target will be. as far as distance, it is also more complicated, and you need to think about your offsets. i.e. if you're trying to hit the A zone on an IPSC head at 10 yards, you would normally hold the top of the head with a 50/200 yard zero, but how do you hold the top of the head with a 6 oclock sight picture? hmm..... |
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If you're zeroing it for xtc matches, the 50/200 will not work. You'll need to establish a true "zero" at all distances, i.e. 2,3, and 600 yards. Zero it at 100, and then add the "come ups" to get on target at 2,3, and 6. Make sure to count the "clicks" up from bottomed-out and record them for future use. Also, use nail polish or a paint pen and mark the elevation index as well. The 3/8 or 3/6 will be basically useless in xtc. Also, zero using your chosen match load(s). |
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As mentioned you need to know of you have a windage adjustable front sight. You also need to know if there is a set screw below the front sight post. If so it needs to be backed off to adjust the front sight height. I usually bottom the rear sight and lower the front post (1 complete revolution each time due to blade taper) until it shoots low then set it one revolution higher so it barely shoots high. That is done at 100 yards. Then I adjust the front sight windage, if adjustable. After that I thread lock the front sight screws. From there all adjustments are made with the rear sight to center on a 100 yard target. Once zeroed, I mark the sight knobs. |
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Originally Posted By pepe-lepew: I usually bottom the rear sight and lower the front post (1 complete revolution each time due to blade taper) until it shoots low then set it one revolution higher so it barely shoots high. That is done at 100 yards. You need to raise the front sight post to make the rifle shoot lower. |
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Set the rear sight so you have a few moa to lower the sight. So maybe four clicks up from the bottom if you have a half moa rear sight elevation. Mechanical zero on the front sight. That’s the sight base flush it the front sight tower base it screws out of. Adjust yours of course in full revolutions with the aforementioned wide face toward your eye. Shoot at your fifty yards. Adjust the front sight height only at this distance, you’re gross sighting in. Leave the rear sight elevation alone. Adjust windage if needed on the back sight. If you have 200 yards or meters range set up at target there. Your front sight is 4x normal square post adjustment. So at 200m (close enough to yards for now) that’s 2 3/4” TIMES FOUR, so that’s 11 inches if you have to move your front sight post it’s full revolution. 5 inches if you’re constrained to a 100 yard range. If you hate that limitation of a using the full rotation NM post you can always swap it for a square M16a2 post for the finer adjustment which is about 1.3 ish MOA. You did not specify if you had a 1/4 x1/4 or 1/2x1/2 or a mixed sight. Some people like the 1/2 moa elevation and a finer 1/4 moa windage. Either way when zero’d at 200 I like to be able to come down if I have too. Oh and if you’re going to change ammo all the time like shoot 55s and 80 grain single loaded ammo you need to think your sight set up through thoroughly. Otherwise you’ll show up to shoot your alternative ammo and bottom out your rear sight and have to hold under at the shorter ranges. Same if you set it to close to bottoming out and you are experimenting with hold point; center mass, six o’clock, line of white or the half blind old man frame hold. At least if you set up with a center mass aim all the others are upward adjustments. |
The only hyphenated names I like are cartridge names......30-06, 30-40, 38-55 etc.
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Oh and a 100 yard and 200 yard sight setting is really close. You could set it up where they both are 10 ring shots with the same sight setting. One a slight bit higher impact than the other. Years ago I shot league shoots where we shot at 100 then 200. Kind of sill but that’s the way we did it. I’d make the expected dope change on my RRA NM rifle and end up dialing it back to the 100 yard setting. It just wasn’t needed and move a little too far, This was the old standard 20” A4 with a 1/4 by 1/4 moa carry handle sight. In hind sight I probably should have done a 1/4 - 1/2 set up. IIRC all I had to do was flip the elevation wheel upside down to do that. It simply has less holes on the other surface for farther detent spacing. That brings up another thought. Once you settle on your ammo choice and how you like to run your sights you can reset the elevation wheel so the numbers line up the way you like. This was more important to guys who liked the meters to match up on the issue type sights. IIRC the NM sights are numbered differently. It’s been a long time since I dragged that rifle out of the back of the safe. 
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The only hyphenated names I like are cartridge names......30-06, 30-40, 38-55 etc.