Possible FSB cant [Archive] - Weapon Evolution

Clarke

30 January 2012, 16:02

I am looking for some input on an upper that I have. It is a 16" mid length upper from a very reputable manufacturer. The issue I have is that it seems the FSB is canted. I have used both a MBUS and a Troy buis with almost identical results, the Troy is almost 20 clicks left to zero. I sent the upper in per the request of manufacturer. and this was the email and the conclusion that they came up with
In this case the FSB is good, but the rear sight is causing the issue. Manipulating the rear sight will give a different look and sight. Please keep us posted after some more range time.

I have used two different BUIS, and also had a friend of mine sight in the rifle, he had almost identical results. I am very happy with the customer service I have received thus far just not sure of the findings, I have owned 3 other uppers from this manufacturer and all were 2-3 clicks of windage to zero. Some thoughts and/or suggestions when I get the upper back?

Thanks in advance

Paulo_Santos

30 January 2012, 18:14

Did you send them the upper with your rear BUIS?

Quib

30 January 2012, 18:50

Clarke

30 January 2012, 18:51

Yes, I sent it in with the Troy.

Clarke

30 January 2012, 19:23

If you have the proper tooling, you might try this procedure- Follow the link below. Scroll down to: BARREL INDEXING AND FSB CANTING

http://www.weaponevolution.com/forum/showthread.php?1613-FAQ-s-BASIC-INSPECTIONS-AND-PROCEDURES

I have the means to re-index if absolutely necessary, since this upper was just purchased, I figured I would send back to them and let them see what they came up with. I was SURE it was going to be a canted FSB. I am at a loss right now. I should be getting it back tomorrow. I was just wanting to see what you guys all thought and if you had any suggestions.

Eric

30 January 2012, 23:17

Who is the manufacturer? I understand that the rear BUIS plays a part in the equation, but if several BUIS display the same problem, the list of potential issues is a lot shorter. 20 clicks is excessive. I'm trying to recall from memory, but I believe that the spec is a max of 12 clicks to the left or right of mechanical zero.

M. Gale

31 January 2012, 04:25

If you have the proper tooling, you might try this procedure- Follow the link below. Scroll down to: BARREL INDEXING AND FSB CANTING

http://www.weaponevolution.com/forum/showthread.php?1613-FAQ-s-BASIC-INSPECTIONS-AND-PROCEDURES

Quib is on to the problem. The barrel assembly needs to be aligned properly in the upper receiver.

bcammons

31 January 2012, 20:31

I have one with a tweaked FSP. The MBUS I have is almost totally maxed out left.

Clarke

3 February 2012, 15:26

I got the upper back this week, will get out to the range asap. Still not sure I am sold on what the findings were. What do you guys think about the email response?

markm

10 February 2012, 04:04

Both of those BUIS sights are piss poor. The TROYs are always popping up with this issue on the various forums.

That said, there still may be an issue with your upper.... But I'd try one last thing.... A real carry handle sight just to make sure..