Follow the steps below to install a 1 piece Aluminum Handguard on your AR rifle.
To install an aluminum one piece handguard you need a vice, Armorer's action block, Armorer's wrench and a strap wrench.
Remove the handguards. The front sight base/gas block with gas tube must be removed by drifting out the two taper pins from left to right. Place the sight base/gas block on a piece of wood for support with the ejection side of the receiver down. Start the pins with a large drift punch to loosen them then drift them out with an 1/8" punch. Tap the base off with a plastic mallet. Place the upper in the action block in a vice and remove barrel nut with Armorer's wrench on a breaker bar. Remove the barrel nut and handguard cap.
Lube the threads of the aluminum handguard with Tetra grease and turn on the handguard as tight as you can by hand. Tighten the tube with the strap wrench until the next one of the holes for the gas tube lines up with the hole in the receiver. Install the sight base/gas block with gas tube onto barrel. Install the taper pins right to left as far as they will go by hand with the ejection side up and then tap them home.
To remove the aluminum handguard you need to remove the gas block with gas tube by drifting out the taper pins. The taper pins drift out left to right. Place the gas block on a piece of wood for support with the ejection side of the receiver down. Start the pins with a 1/4" drift punch then drift them out with a 1/8" drift punch. Tap the gas block with gas tube off the barrel with a plastic mallet.
Place the upper receiver in an Armorer's action block and then the block in a vise. Remove the handguard with a strap wrench by unscrewing the handguard counter clockwise.