HELP!!! A2 rear sight issues EDIT new question added - Page 1

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[ARCHIVED THREAD] - HELP!!! A2 rear sight issues EDIT new question added

Posted: 10/26/2014 7:30:49 PM EDT

So I just got in an A2 20" upper. I was checking out to see what the rear sight was set for when I noticed something. The rear sight block is twisted to the left (see picture) and I have no idea to get it to un-turn. If I physically try and turn it so it points straight down the carry handle, it springs back to being crooked. I have looked at pictures and videos of zeroing A2 sights and none of the dials seem to physically turn the sight block. What do I do??? PLEASE HELP.

Edit: When I adjust the elevation up is it supposed to straighten out? Cause I was playing with it and as I adjust the sight up it slowly straightens. Wouldn't that effect accuracy??? And for those who wanna know it is an older bushmaster. One I havent seen in production since before the buy out.

Pictures taken at the lowest 8/3 setting.

Posted: 10/26/2014 8:02:13 PM EDT

[#1]

Normal, and it's supposed to be that way.

Nothing wrong with your rear sight.

Posted: 10/26/2014 8:08:40 PM EDT

[#2]

This is actually quite normal. Some sights seem to exibit it more than others, but just about all A2 sights are canted like that to some degree.

You can kind of see in your second photo that there is a small ball bearing (to the left of the tip of the "up" arrow) that has a spring behind it that pushes the sight away from the carry handle. This removes any "slop" between the rear sight and carry handle, so the rear sight will always be in the same position.

Again, it is nothing to worry about and it will not affect accuracy in the least.

Posted: 10/26/2014 8:18:01 PM EDT

[#3]

That is crazy. If you can't tell it is my first A2. I have fallen in love with it. But I was freaking out when I saw that. Never seen anything like it before. When I adjust the elevation up is it supposed to straighten out? Cause I was playing with it and as I adjust the sight up it slowly straightens. Wouldn't thaf effect accuracy???

Posted: 10/26/2014 8:24:58 PM EDT

[#4]

This is normal. Some are canted a bit more than others. Shoot it and enjoy!

Posted: 10/26/2014 9:28:28 PM EDT

[#5]

It is made that way on purpose. It is to allow for different manufacturing tolerances, and to allow the sight freedom (space) to make elevation adjustment easy, and also to make sure sight is always consistent in location.

Posted: 10/26/2014 9:35:11 PM EDT

[#6]

Read me ---> http://www.armalite.com/images/Tech%20Notes%5CTech%20Note%2018,%20M16A2%20Rear%20Sights,%20960729.pdf

Posted: 10/26/2014 10:06:02 PM EDT

[#7]

Like said already some are more canted than others. If it drives you crazy you can get a National Match rear sight from Accuracy Speaks that has a nub opposing the plunger that you file down until the sight sits straight. They are spendy.

Posted: 10/27/2014 4:16:01 AM EDT

[#8]

Quote History

Quoted:
Like said already some are more canted than others. If it drives you crazy you can get a National Match rear sight from Accuracy Speaks that has a nub opposing the plunger that you file down until the sight sits straight. They are spendy.

View Quote

For sure! Standard rear sight assembly is $38 or so new, NM rear sight assembly is $159 or so new.

Posted: 10/27/2014 8:39:03 AM EDT

[#9]

Quoted:
So I just got in an A2 20" upper. I was checking out to see what the rear sight was set for when I noticed something. The rear sight block is twisted to the left (see picture) and I have no idea to get it to un-turn. If I physically try and turn it so it points straight down the carry handle, it springs back to being crooked. I have looked at pictures and videos of zeroing A2 sights and none of the dials seem to physically turn the sight block. What do I do??? PLEASE HELP.

Pictures taken at the lowest 8/3 setting.

http://i1257.photobucket.com/albums/ii512/WatermelonAssassin/IMG_1211_zpsfa5b64e2.jpg
http://i1257.photobucket.com/albums/ii512/WatermelonAssassin/IMG_1212_zps594b95a0.jpg

View Quote

A little cant is expected, but yours is unsatisfactory. No good reason for that much "tolerance." Send it back or exchange out the base.
By the way, what brand of A2?

Posted: 10/27/2014 11:40:38 AM EDT

[#10]

I have both Colt and Bushmaster A2 uppers from the 2000s. The Colt looks like OP's pic, the BM is slightly better. Not sure if there is a spec for this but I'm guessing it's pretty loose if there is one.

Posted: 10/28/2014 8:39:46 AM EDT

[#11]

Quote History

Quoted:

A little cant is expected, but yours is unsatisfactory. No good reason for that much "tolerance." Send it back or exchange out the base.
By the way, what brand of A2?

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
So I just got in an A2 20" upper. I was checking out to see what the rear sight was set for when I noticed something. The rear sight block is twisted to the left (see picture) and I have no idea to get it to un-turn. If I physically try and turn it so it points straight down the carry handle, it springs back to being crooked. I have looked at pictures and videos of zeroing A2 sights and none of the dials seem to physically turn the sight block. What do I do??? PLEASE HELP.

Pictures taken at the lowest 8/3 setting.

http://i1257.photobucket.com/albums/ii512/WatermelonAssassin/IMG_1211_zpsfa5b64e2.jpg
http://i1257.photobucket.com/albums/ii512/WatermelonAssassin/IMG_1212_zps594b95a0.jpg

A little cant is expected, but yours is unsatisfactory. No good reason for that much "tolerance." Send it back or exchange out the base.
By the way, what brand of A2?

I hope it is not one of the ASA A2 uppers I just ordered.

Posted: 10/28/2014 9:59:28 AM EDT

[#12]

Where else could you ask a question about the A2 and get an answer from the guy responsible for the design of the A2.

Always great to hear from the LTC.

Posted: 10/28/2014 12:36:29 PM EDT

[#13]

No, it isn't an ASA. It is a much older bushmaster from before the buy out. Back when bushmaster was bushmaster. I don't know if they would still honor any warranty work on it. And I had asked higher up but don't know if anyone saw it. As I adjust the elevation nob under the sight, it slowly straightens out as it rises. Until it is perfectly straight at maximum elevation. Is that also normal? And wouldn't that effect accuracy?

Posted: 10/28/2014 1:20:05 PM EDT

[#14]

I'll have to relook at all of mine now, but that looks ridiculous to me. I have an A2, and a few different A2 removable sights for flat tops and I don't think any of them look anywhere near that canted. If at all. So...... I'm with coldblue, that is a LOT of movement and yeah, I would think it would affect accuracy at least a little.

Posted: 10/28/2014 2:13:47 PM EDT

[#15]

I will contact bushmaster and see what they have to say.

Posted: 10/29/2014 1:27:38 PM EDT

[#16]

I have stuck shim stock in the gap to even it up before. I have also contemplated drilling and tapping a small #4 or #2 hole in the aluminum and using a little brass or nylon set screw for the sight to bear onto to even it up. I have also shot crap-loads of rounds with it cocked over and like everyone says it seems to make no difference. The total cocked angle is so small that the resultant "ovalization" of the peep hole is trivial and not a factor. Your eye naturally finds the center either way.

Posted: 11/1/2014 6:27:02 PM EDT

[#17]

I heard back from bushmaster their reply was "We can't do anything." So I will just sell the upper. Going to build a 20" with a BCM M4 upper and 20" service rifle barrel I just got from White Oak Armament. It's going to be a laser/M16A4 clone.

Posted: 11/2/2014 12:31:40 AM EDT

[#18]

Is it Govt' profile?

Posted: 11/3/2014 2:40:54 PM EDT

[#19]

No it is H-Bar. I prefer H-bar anyway. I find the weight difference is marginal compared to the benefits. Although I have a friend that does professional barrel fluting, that offered to flute it for free. Seriously contemplating that....

Posted: 11/3/2014 5:14:07 PM EDT

[#20]

That would be nice I think. I really don't like 20" Hbars. You must be Arnold Schwarzenneger. LOL.

Posted: 11/3/2014 11:25:42 PM EDT

[#21]

Quote History

Quoted:
That would be nice I think. I really don't like 20" Hbars. You must be Arnold Schwarzenneger. LOL.

View Quote

Hahaha I am not Arnold Schwarzenegger. When I first got into guns I would haul old Mausers and such around with me in the woods. Those are easily 9-10lbs unloaded. Then I upgraded to a Sig716 which is also like 9-10lbs unloaded. So for me an AR with a 20" HBAR isn't much of anything. Besides I long ago learned that a good sling can turn a walk in the woods from a 15lb hauling death march to a fun adventure. I am hoping to use this 20" HBAR as a longer range AR-15 platform as I am currently lacking a good mid to long varmint gun.

Another question for the wiser sorts. What use is pinning an A2 sight? White oak has some nice National match rear assemblies that I could swap onto the bushmaster to replace that sloppy one. But I don't know if I want pinned or not...

Posted: 11/4/2014 9:19:27 AM EDT

[#22]

Here is my advice. Buy a Arma light 1/2x1/2 match rear sight. It costs around 80 bucks. Buy a Schuster engineering a2 instalation tool.

The Arma light nm sight has a raised Ridge that will help straighten the cant on the rear sight. Since it's the same thread pitch as the gi aperture you could replace the National match peep with the a2 peep.

Then you have reduced your cant on your sight, given yourself a finer elevation adjustment, and you now have all the tools to install these sights in the future. Now you just need a preferred load and a bullet drop calculator and you can map out the dope on your sight with a marker.

That's what I did and it worked out great. I shot it in a high power match and satisfied myself that I can run next to the big boys without all the extra fancy gear.

Posted: 11/13/2014 1:53:38 AM EDT

[#23]

I just posted a National Match rear AR sight for $65.00 Its like new, and I have no use for it.
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[ARCHIVED THREAD] - HELP!!! A2 rear sight issues EDIT new question added

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