Ok so I have a DPMS AP4. The front sight base is a pain to come off. Is it possible to shave it down and leave it on the barrel, then change out the free float it has now with a VTAC/JP handguard. Or will the installation of the new handguard require the gas block to be off? If so I will have a gunsmith complete the process as it is hard to get off the FSB and I do not want to mushroom out the set pins.