As long as you didn't enlarge the holes in the FSB during the removal process, or damage the taper pin grooves in the barrel, you should be good to go. I have done it for several customers that wanted to change out the handguards for a free float system. If the holes in the FSB have been damaged I just tap them with a 8/32 tap and use headless set screws to reset the FSB. Once you have done it a couple of times it's no big deal.