Canted front sight base - easy fix?

[kbf64]

I think I got an upper with an ever so slightly canted front sight base. Is this an easy fix to send it in for? Just trying to weight repairing it locally or shipping back to manufacturer.

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[edzz]

How is the base attached? Screwed? Pined?

 

[msgriff]

I think I got an upper with an ever so slightly canted front sight base. Is this an easy fix to send it in for? Just trying to weight repairing it locally or shipping back to manufacturer.

There seems to be an increase of this problem lately, even from higher end Mfg's. It can be a simple fix if very slightly canted, but you would have to remove the barrel nut to know. If the FSB was not aligned correctly to the barrel extension index pin when drilled and pinned, it's a much more difficult job, and should be done by a specialist or experienced gunsmith.. It may also be within that Mfg's spec, so a replacement barrel or upper may not be any better. I would be happy to explain the procedure if you were wanting to do it yourself, but it does require some basic gunsmith tools and supplies.

 

[kbf64]

I think it's pinned, was thinking it may still zero, though I'd lose windage out of it.

 

[Berlinettaa]

I had an upper from PSA last year that was canted, filing the barrel alignment pin ever so slightly fixed it. Driving out FSB pins can be tricky but is doable with basic tools and skills, that is the only tough part of the process. If you plan on using an optic however, it is not necessary as there is enough windage adjustment for the purpose of back up irons. Toss on a red dot or LVPO and be on your way.

 

[kbf64]

so I disassembled tonight and it looks like the index tab on the barrel was a little loose inside the upper receiver. So without the nut you can tilt it to one side. I held it upright and tightened the nut back down, doubt that's a long term fix.

I think I could get a metal shim in there so that it can't rotate ever so slightly to the left due to the play in the upper receiver. Probably last FSB I will buy however...

 

[StacattoP]

What brand was the upper?

 

[Aongus]

so I disassembled tonight and it looks like the index tab on the barrel was a little loose inside the upper receiver. So without the nut you can tilt it to one side. I held it upright and tightened the nut back down, doubt that's a long term fix.

I think I could get a metal shim in there so that it can't rotate ever so slightly to the left due to the play in the upper receiver. Probably last FSB I will buy however...

So are you saying the barrel moved? Or is the barrel extension not plumb? When you torque down the barrel nut, my understanding is 30footlbs to 80footlbs is your range, just a heads up.

 

[kbf64]

PSA upper, yeah looks like the barrel moved a few degrees because the tab on the barrel isn't snug in the upper receiver. So with some shooting it will probably not stay in place.

I have an RMA to return it...

 

[Member 5605]

I've grabbed my FSB and just gave it a hard twist to correct. Usually it fixes it.

Gorilla hands.

 

[kbf64]

Well, I'm now not a fan of FSB as it's way easier to go low profile, and have a flip up sight on a rail.

 

[kbf64]

long live aero precision builder sets!!

 

[titsonritz]

Well, I'm now not a fan of FSB as it's way easier to go low profile, and have a flip up sight on a rail.

Don't blame FSBs, the problem is a POS PSA upper. Exchange it, maybe you'll get lucky next time.

 

[Berlinettaa]

Don't blame FSBs, the problem is a POS PSA upper. Exchange it, maybe you'll get lucky next time.

True, they have a tendency towards low QC. You get what you pay for in this case. I just finished a build with areo upper and ballistic advantage barrel and it was much better quality finish, machining, and overall fit.

 

[Member 34319]

I've had 3-4 manufacturers cant front sights blocks. If the barrel isn't in a proper jig or whatnot, the holes for the block get drilled off.

I've never had one far enough over to where I couldn't adjust a rear sight to work with it.

 

[titsonritz]

I've had 3-4 manufacturers cant front sights blocks. If the barrel isn't in a proper jig or whatnot, the holes for the block get drilled off.

I've never had one far enough over to where I couldn't adjust a rear sight to work with it.

The military tech manual spells out a tolerance for this specific thing, don't have the time to look it up at the moment.

 

[thorborg]

Sometimes, a bigger hammer

 

[Geardo]

Don't blame FSBs, the problem is a POS PSA upper. Exchange it, maybe you'll get lucky next time.

My BCM Kino FSB is canted too. Its not just PSA.

They gave me and RMa to send it in but I am just so lazy.

 

[AK0perator47]

Guess my cheap Bushmaster I bought that Remington put together after buying the company from the original Windham Maine Bushmaster is better than a BCM!

not canted and works perfectly