I have one on one of my uppers, if I remember right it's the
RRA. I liked that one because it puts the sling stud right under the front sight base.
To install you will need a receiver
action block,
Universal Barrel Wrench,
1/16" punch , a Dremel tool w/cut off disk and grinding stone,
Torque wrench, a
snap ring pliers, and I'd suggest the US Marine Corp M16A2
manual. Just follow the links to find all the tools.
For install you will have to cut off the ears on the front sight base that hold the sling swivel since the RRA's tube mounts the swivel in the same location.
Tap out the gas tube roll pin with 1/16" punch; wiggle the tube out with a set of needle nose pliers if you need to.
To get the FSB off drive out the taper pins from the bolt catch side of the rifle to the ejection port side of the rifle.
Mount the receiver in the action block the clamp in a bench vise. Take your barrel wrench and turn the BBL nut counter clockwise facing the muzzle. You will have to use the snap ring pliers to remove the handguard slip ring assembly and move it over the the new Float tube BBL nut. Install your new BBL nut that came on the float tube on the BBL and torque the BBL nut to 35 Ft lbs. 3 times. Then move the nut to the next notch if the BBL nut blocks the area where the gas tube slips into the upper.
Take the dremel tool with the cut off blade and cut the swivel ears off the FSB, touch up with some cold bluing.
Therad the lock coller on to the barrel nut all the way to the bottom of the BBL nut. Put some
blue loctite compound on the threads and thread the float tube onto the BBL nut. Slide on the FSB to where the taper pins should go in the barrel and then thread the tube out to the FSB so there is clearance between the FEB and the fron of the float tube. Then use the CAR wrench (hook looking thing) on the barrel wrench listed above to snug the lock coller to the back of the float tube.
Install the FSB on the BBL (Use a little CLP oil on the taper pins).
Now remove the heat shields from the hand guards and toss them out. Now you will have to remove some material from the front of the hand guards with the grinding stone or burr bit. The area you're looking to remove is the inside diameter hole where the barrel passes through the hand guards. The float tube has a larger Diameter than the barrel thus the HG's wont fit.
Once that's done install the gas tube w/ roll pin. Line up the gas tube with the bolt carrier key buy using a Lg flat blade screwdriver to flex the gas tube so it mates w/the carrier key perfectly.
And you should be good to go!