It's come time to re-barrel my service rifle. It's based on Bushmaster upper and lower and has a Bushmaster free-float tube (#F1000535). My question is, is the float tube and barrel nut one piece that come off together or does the tube screw off first and than the barrel nut last? Looking at it, I'm just not sure. Tried spinning the tube with a strap wrench but it didn't budge. For once, I'm trying to be patient.