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View Full Version : windage adjustment -- how far is too far?



Bill Bryant
24 October 2009, 15:23
How far from a visual "center" would a windage adjustment have to be for some of you experienced AR people to think that maybe there's a problem elsewhere in the gun's set up that needs to be addressed? I zeroed a rifle today and ended up with an MBUS looking like this.

Cause for concern? Indication of anything to be worried about?

http://i172.photobucket.com/albums/w36/ttkt57/IMG_1456.jpg

http://i172.photobucket.com/albums/w36/ttkt57/IMG_1462.jpg

Quib
24 October 2009, 15:31
As long as the BUIS windage is not maxed out, and you were able to successfully zero, you should be fine.

A rear sight aperture off to one side a significant amount, is usually a good indicator of a barrel indexing problem, or a canted FSB.

Paulo_Santos
24 October 2009, 15:50
No problem at all. My rear Troy Buis was really far to the left with my LMT MRP upper and i had no problem with it. It was annoying, but nothing else.

OfcPowder
24 October 2009, 19:34
It may just be the way you're viewing the rifle through the sites. Maybe it's not the sigths, maybe your eyes are off. [wow]

Bill Bryant
24 October 2009, 19:51
It may just be the way you're viewing the rifle through the sites. Maybe it's not the sigths, maybe your eyes are off. [wow]I'm starting to think this may be true. I'm 52, I'm near-sighted, and I have astigmatism. My correction is tri-focals, and I often have to take them off to shoot because I can't focus on the front sight with my glasses set correcly on my face.

I tried an experiment when I got home from the range. I clamped the upper in a padded vise and pasted an orange dot on a wall 20 feet away, directly down the bore line. I then put a piece of paper on the wall directly above the orange dot with a vertical black line directly above the orange dot. Then I looked through my MBUS, and wow was it off! In order to put the iron sights back in line--lined up with the vertical line directly above the orange dot lined up with the bore--I had to click the MBUS back to something very close to the center.

I'm beginning to think my iron sight days are over.

Anybody have a spare Aimpoint or ACOG lying around they'd let go for under $50? [:D]

Paulo_Santos
24 October 2009, 21:06
From what position are you zeroing your AR? That will also make a differnce. I used to zero my AR from the bench, but I would be off a little when shooting prone, kneeling and standing. So now I zero from the prone and it is much better. The only time I would zero from the bench would be if it was just a bench gun.

Bill Bryant
24 October 2009, 21:51
From what position are you zeroing your AR? That will also make a differnce. I used to zero my AR from the bench, but I would be off a little when shooting prone, kneeling and standing. So now I zero from the prone and it is much better. The only time I would zero from the bench would be if it was just a bench gun.I zeroed from prone.

Paulo_Santos
24 October 2009, 22:11
I zeroed from prone.

As long as you are hitting your target, I wouldn't worry about it then.

cmoore
26 October 2009, 03:37
That's not uncommon brother. A guy in my unit had an M4 zeroed and about two clicks from a dead stop-far left. He shot fine like that. Take into account your position when you zeroed and make sure you "mount" the same each time.

Best regards...

d30gaijin
1 November 2009, 08:46
How far from a visual "center" would a windage adjustment have to be for some of you experienced AR people to think that maybe there's a problem elsewhere in the gun's set up that needs to be addressed? I zeroed a rifle today and ended up with an MBUS looking like this.

Cause for concern? Indication of anything to be worried about?



Not a cause for concern but fairly easy to fix. Loosen the front sight base and cant it to the right a tad then rezero the rear sight. If it is a milspec front sight base held in place with taper pins then you're kind of stuck with it as is, even at that it can be fixed to cant the FSB to the right but it isn't really worth the hassle.

Don

Quib
1 November 2009, 09:12
For those interested, I address “FSB Canting” and “Barrel Indexing” in the thread below:

http://www.weaponevolution.com/forum/showthread.php?t=1613

Bill Bryant
13 November 2009, 20:47
I'm posting these additional pictures to show part of the process I've used to confirm that there is no significant front sight cant. I went further, after taking these pics, using longer precision straight edges, dial calipers, and other tools, and confirmed to myself that front sight canting is definitely not what caused the need for the BUIS sight to be dialed so far to the left. I'm developing other theories, but none satisfy at this point.

I should also mention that I bore sighted the rifle in my large basement, using a perfectly verticle line on a wall thirty-five feet away with the gun in a vise and measured level. Using this system, I had to dial the MBUS back to a visibly centered location.

I haven't been back to the range, and I've now sold the MBUS for a KAC micro 200-600 buis which should be arriving in a day or so.

This time I'm going to start by bore sighting and then see if the KAC sight also bore sights close to center and then ends up over to the left when I get to the range and actually shoot some rounds.

BTW if you haven't had a close look at parts from BCM, you really should. A close inspection of my BCM upper, barrel, and BCG is really impressive to this old machine shop guy.

http://i172.photobucket.com/albums/w36/ttkt57/IMG_1485.jpg

http://i172.photobucket.com/albums/w36/ttkt57/IMG_1493.jpg

http://i172.photobucket.com/albums/w36/ttkt57/IMG_1488.jpg