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anotherted
02-27-2007, 8:43 PM
...having to adjust my windage on my AR all the way to the right just to get on paper at 100 yds? I was reading that sometimes, due to an indexing problem, the front site post can become canted. Ive also read that this is a serious problem. Is this correct? Any ideas as to what might be happening? Oh....I love the simplicity of my M1A.:o

kj
02-27-2007, 9:07 PM
It could either be an indexing problem with the barrel/indexing pin or the front sight tower. If the barrel was torqued on too tight, it could have bent the indexing pin (but I think that would require left windage). Also, the front sight could be mounted off-center. If you can return it for repairs, that would be the easiest. If not, you're gonna need the tools and vise blocks to reindex the barrel, or a windage adjustable front sight tower.

E Pluribus Unum
02-27-2007, 9:12 PM
...having to adjust my windage on my AR all the way to the right just to get on paper at 100 yds? I was reading that sometimes, due to an indexing problem, the front site post can become canted. Ive also read that this is a serious problem. Is this correct? Any ideas as to what might be happening? Oh....I love the simplicity of my M1A.:o

My M1A has that issue. I can send it back to SA to have them fix it but why? It works fine and I use the scope anyway....


I was able to adjust my front sight to compensate; are you not able to?

anotherted
02-27-2007, 9:14 PM
My M1A has that issue. I can send it back to SA to have them fix it but why? It works fine and I use the scope anyway....


I was able to adjust my front sight to compensate; are you not able to?

Im talking about my AR, not my M1A. I was just saying how i like that you
can adjust the front sight for windage on an M1A.

alpha_romeo_XV
02-27-2007, 9:21 PM
If you have screws clamping the bottom of your gas block its very easy. just back off the screws a half turn on the side you need to rotate the FS post towards and then tighten the two screws on the opposite side. Don't loosen both sides at once! You totally loose zero. While at the range, put your rear sight in the middle and work those front screws slowly till your shots are on the bulleyes at 50 yrds. If you have rivets on the gas block then ? use a mallet ?
http://i144.photobucket.com/albums/r182/wiskeypapa57/temp2/ARsling.jpg

kap
02-27-2007, 9:21 PM
What is the setup on your AR?

Just a thought, but if you have a railed gas block and installed your front sight backwards it can have that effect.

anotherted
02-27-2007, 9:29 PM
Standard A2 sights.

xenophobe
02-27-2007, 9:44 PM
If your rear sight isn't somewhat aligned, then your barrel is not square to the receiver. Send it back.

I know that this is bad advice, but you can put the receiver in a receiver block and bend the barrel the direction the rear sight is moved towards. No joke. This is how Colt does it.

SuperSet
02-27-2007, 9:48 PM
My buddy's Bushmaster upper had this problem and it was finally resolved by sending it into BM for them to correct the front sight.

hoffmang
02-27-2007, 9:52 PM
I have the same problem on one of my beater uppers.

Xeno, I know you said you are serious, but wow...

-Gene

anotherted
02-27-2007, 10:21 PM
Im just gonna call CMMG tomorrow.

hoffmang
02-27-2007, 10:24 PM
My "beater" is an M1 sales so I kind of expect it...

-Gene

cornholio1
02-27-2007, 10:30 PM
Q: I've zeroed my rifle, but my rear sight is all the way to one side! How do I fix this?

A: What is there to fix? As long as the rifle is zeroed and is reliable then the problem is merely a cosmetic one. In most cases it is due to a improperly torqued barrel, and retorquing the barrel properly will fix it. In some of these cases if the barrel was over torqued the index pin may have bent or sheared off the barrel in which case you will have to pull (or drill it out) and get a new one [Bushmaster sells these]. Most AR manufacturers will fix the problem for free. In a few rare cases the front sight/gas block may be put on crooked, but in these cases the rifles have unreliable or non existant functioning. The manufacturer will need to fix this. Also, in a few cases you could have the slot for the index pin too large (due to either an ingnorant gunsmith or a very poor upper receiver) you will either have to retorque the barrel very carefully or replace the receiver.

http://groups.msn.com/TheMarylandAR15ShootersSite/maintenacefaq.msnw

adamsreeftank
02-27-2007, 11:38 PM
If your front sight base uses screws, then it is an easy fix.

If it uses tapered pins, then the "best" way to fix it is to loosen the barrel nut and rotate the barrel into proper alignment. Then to re-tighten the nut, you need two vises. One with an action block holding the receiver and one with a barrel block keeping it from rotating. A torque wrench "should" be used to do it right.

Unless you have these tools and know how to use them, it would probably be best to send the upper back. Most uppers have the rear sight off to one side with the gun zero'd, but mil-spec calls for a certain allowable range. If it is ALL the way over, then it is out of spec.

xenophobe
02-28-2007, 12:18 AM
I have the same problem on one of my beater uppers.

Xeno, I know you said you are serious, but wow...

-Gene

Yeah, I know it sounds like the most mickey mouse hack, and it is. But that is what they do on the Colt production line, and it's been documented and proven.

Of course, I shouldn't suggest anyone do this that doesn't have the proper tools... lol

m24armorer
02-28-2007, 5:02 AM
Generally there are four ways the front sight is installed.

1. Allen screws.
2. Roll pins.
3. Straight dowel pins.
4. Taper pins.

As long as the notch in the upper is not butchered from someone installing the barrel it is really a simple fix. The front sight has to be rotated and the pins replaced. If you have allen screws just loosen them and turn the sight.

With pins you have to go oversize. Get rid of the roll pins if you have them and replace them with solid or tapered ones. This does require reamers and a alignment rod. Simple fix with the right tools.

MustangO4
02-28-2007, 5:25 AM
If you want to hear really Micky Mouse. I have one REAL beater upper that was pieced together from spare parts and just wouldn't line up. So, out come the pins, get it lined up and WELD it in place. Can't ever take it apart, but it ain't going anywhere.

I say just send it back and let them worry about it, or hack off the front sight and tell yourself you wanted it like that anyhow.....

pc_city
02-28-2007, 8:06 AM
My Bushmaster upper had the same problem until I replaced the flash hider with a muzzle brake. I'm guessing that Bushmaster overtorqued the barrel while mashing down the crush washer.

anotherted
02-28-2007, 8:23 AM
Although I thought about dusting off the sledge, Ive decided to send it back to CMMG instead. :o