I installed a used Bushie barrel into a used DPMS upper and the FSB (or barrel?) is canted to the right.  I have read the FAQs and did a search and am still confused about the solution?  Any help would be appreciated.

Thanks

You need to put your upper in a barrel Vise Block and smack the upper receiver on  the left front to the right just alittle to remove the cant. or else put the upper in a reiver block and smack the FSB on the right towards the left with a nomar hammer. I had the same problem now it is straight.

I found this on the Bushmaster web site a few minutes ago:

This is a problem that took us some time to figure out but it is so simple, we're kicking ourselves. The little index pin that lines up the upper and lower is very soft, so that it can shear off if the barrel is over-torque. This is to prevent damage to the receiver when barreling. This pin will distort slightly before it snaps, and this slight distortion is enough to create the excessive windage you describe. A new pin costs only $1.50 and removing the old pin is as easy as grabbing onto it with vise grips and twisting it up and out. Drive a new one in and try the upper on. The pin may shear when you try to remove it, but they are easy to drill out. Just be sure not to drill into the barrel extension. A new pin will be like having a brand new barrel (as far as the receiver is concerned, it is new) and that windage problem should disappear.

Thought this might help you...might be your problem although I have heard several folks complaining about this exact problem with Bushmaster barrels. I have somewhat the same problem only my pin is not bent or distorted. And I'm sure I didn't over torque the barrel nut.

What about filing the index pin instead of the receiver?  

The main thing I don't understand is where to peen the receiver.

Can't help you on the do-it-yourself technique, but I present you another option anyway. I recently had the same issue with a 1/7 twist BM barrel. I contacted BM and spoke with Jim Eden. He's the head gunsmith. He said send the upper in with my iron sights and they'd straighten it out. They redrilled the pin-holes and put in slight oversize pins. When I got it back, it was dead on at 50m, center windage and he included the sight-in target to boot. Even better, they didn't charge me a thing. I just had to wait a few weeks for them to get to it.

OK well, I did the beat it with a mallet trick and it seemed to wrok alright.  Now I will shoot it and see where it impacts.