Front sight block help

I just finished my first AR build and used a brand new barrel assembly with preinstalled FSB. Once I got everything together, there is excessive front sight cant to the right. If you look through the mini ACOG on the carry handle and focus on the front sight ears, you will notice that the sight ears are on the right side of the scope picture. I know a little bit of cant can be dealt with but this is quite a bit more than the BCM and DD I have.

Do you guys have any suggestions for gunsmiths to fix this and do a once over on this upper? I used a Del-Ton barrel assembly and used Bushmaster fixed carry handle A2 upper.

Thanks a lot.

Was there excess play between the barrel indexing pin and the upper receiver alignment slot when you installed it? If so, then you should check to see if the slot has excess play in it. If so, you need to replace it.

If that isn't the case and the alignment pin isn't damaged then the FSB is canted and you need to send the barrel back.

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Originally Posted by 256JSR

I just finished my first AR build and used a brand new barrel assembly with preinstalled FSB. Once I got everything together, there is excessive front sight cant to the right. If you look through the mini ACOG on the carry handle and focus on the front sight ears, you will notice that the sight ears are on the right side of the scope picture. I know a little bit of cant can be dealt with but this is quite a bit more than the BCM and DD I have.

Do you guys have any suggestions for gunsmiths to fix this and do a once over on this upper? I used a Del-Ton barrel assembly and used Bushmaster fixed carry handle A2 upper.

Thanks a lot.

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There was a very small amount of play in the upper index slot but no where near enough to cause this much cant or a problem with the feed ramp alignment. You could feel some movement if you twisted the barrel back and forth by hand but you couldn't tell visually.

I'll keep at it trying to get this barrel checked out back at the mfg.

Thanks for the response!

Not sure how keen your eye is. But look down the top of the barrel using the index pin as your top dead center point. You may be able to see if the FSB is not right if it's that bad.

When I originally looked down the barrel using the index pin I could tell it wasn't perfect but didn't look to be anything too bad.

I went back out to confirm zero and once again took 0 windage adjustments from mechanical zero on the carry handle A2 sight (sight angles counter clockwise slightly). Something definitely isn't straight but I guess if it shoots straight don't fool with it.