Over the last 18 years of working with, and building uppers, I have gotten increasingly disappointed with the commercially available float-tubes on the market. Most are of the two-piece design that forces you to accept whatever torque you end up with when the barrel-nut is correctly timed-up to the receiver. My new float-tube has a two-piece barrel-nut that allows you to get perfect alignment for the gas-tube, without respect to torque. This also allows you to have the vents and sling-stud always time-up perfectly. The float-tube can be installed. removed and reinstalled as many times as you wish, and you will never have to worry about your sling-stud ending up anywhere but bottom-dead-center!
Mounting Instructions and Tips:
Step: 1) once you have the old free float-tube and/or barrel nut removed, clean any grease or oil from the threads of the upper receiver extension.
Step: 2) apply a drop or two of blue LocTite® to the receiver threads and screw the large aluminum barrel-nut on until it stops, then back it off a ¼ to ½ turn.
Step: 3) insert the barrel and slide the steel insert over the barrel and thread it into the aluminum barrel-nut; now, back the aluminum barrel-nut up so that it is about 2 or 3 holes away from lining up with the gas-tube hole in the upper receiver.
Step 4) turn the barrel-nut and insert by hand until you get a good, solid hand-tight alignment with the barrel-nut and receiver. Once you have got the two aligned, let it sit for a couple of hours; after the blue LocTite® has cured between the barrel-nut and receiver, the steel insert and barrel can be removed.
Step 5) place a drop or two of blue LocTite® on the barrel extension and rotate the barrel as you insert it into the receiver. thread the steel insert into the barrel-nut and once it is finger tight, back it off three or four turns and place a drop of blue LocTite® on the threads of the steel insert, right where it becomes visible out of the barrel-nut.
Step 6) now torque the steel insert down to desired torque. This can all be accomplished without letting the Loc-Tite® on the receiver setting up, but the barrel-nut can move while you are torquing the insert, and then you will have to loosen it up and re-time it.
Step 7) once you have installed the tube, and aligned the 6 radial holes with the corresponding holes in the barrel-nut, the 6 countersunk screws can be installed. I highly recommend applying some grease or anti-seize to the threads and tapered holding area of the screws.