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How do I install or remove the B.M.A.S. handguard?

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Overview

Follow the steps below to install or remove the B.M.A.S. handguard.

 

To install an aluminum handguard you need a vise ( 4" minimum ), 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 then drift them out with an 1/8" punch. Tap the base off with a plastic mallet. Remove the handguard cap. Place the upper in the action block in a vice and remove barrel nut with Armorer's wrench on a breaker bar.

 

The B.M.A.S. three piece handguard is installed by placing the upper receiver in an Armorer's Action Clamp in a vise. The barrel nut threads are lubed with Tetra Grease and the nut installed with an Armorer's Wrench to 32 to 45 ft lbs until one of the holes in the nut lines up with one of the holes in it and the upper receiver for the gas tube. The locking ring is turned on all the way on to the rear of the barrel nut and the forward tube is threaded onto the barrel nut. To index the tube it is backed off to about 45 degrees from the rails lining up. The locking ring is turned until it contacts the tube. A strap wrench is then used to tighten and align the tube onto the locking ring. The gas block or front sight base with gas tube is then installed. Taper pins should be installed right to left as far as possible by hand then set with a drift punch while the sight base is supported on a block of wood with the ejection side of the receiver up.

 

To remove the forward tube the upper receiver is placed in an Armorer's Action Clamp in a vise. A strap wrench is used to loosen the forward tube. After it is loose it can be unscrewed from the barrel nut. To reinstall the locking ring is turned on all the way on and the forward tube is threaded onto the barrel nut. To index the tube it is backed off to about 45 degrees from the rails lining up. The locking ring is turned until it contacts the tube. A strap wrench is then used to tighten and align the tube onto the locking ring.

 

It is not recommended to remove the handguard for cleaning unless absolutely necessary and definitely not without the proper equipment so that it can be reinstalled correctly.

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