I have a RRA mid-length I bought on-line. It came with the RRA aluminum free-float tube. I want to replace the tube with a MOE handguard. How can I tell if the flash hider is permanently pinned in place or not? I don't see any screws or welds or anything, but if it's permanently pinned I won't be able to remove the front sight assembly. Also, I'm going to have to replace the barrel nut and install a delta ring, correct? Thanks for the help!