A qualified gunsmith familiar with your firearm should install this forearm. Failure
to install this forearm correctly voids any warranties of the product and removes
any liabilities against the manufacturer. This forearm cannot be installed on a rifle
utilizing a pinned, welded, or otherwise permanently mounted muzzle accessory
unless a two-piece gas block will also be installed. Be certain the firearm is unloaded
and always pointing in a safe direction before starting this removal and installation
process.
(1) Remove the existing forearm per the firearms manufacturer’s instructions.
(2) Unscrew the muzzle brake or flash hider and set aside if one has been installed
on the firearm.
(3) Remove the front sight by tapping out the 2 tapered dowel pins at the bottom of
the sight that hold it onto the barrel using a 1/8 diameter drift pin punch being
sure to drive the pin out from the SMALL END
(4) Remove the sight assembly and gas tube from the barrel and set aside. Retain the
tapered dowel pins for re-assembly.
(5) Remove the front plate of the old forearm and set aside.
(6) Remove the combination delta ring /barrel nut using a proper armorer’s barrel
nut removal wrench.
(7) Clean the threads on the upper receiver and install the new barrel nut until it is
firmly tightened by hand.
(8) Using our forearm wrench YHM-9621 tighten the barrel nut to the next aligning
gas tube hole in the barrel nut and upper receiver. Take special care in aligning
the gas tube hole as this will influence the orientation of the rails of your new
forearm.
(9) Install the jamb nut all the way on the barrel nut until it is flush with the end of
the barrel nut closest to the upper receiver. Then unscrew it towards the muzzle
one and one half turns.
(10) Install the forearm onto the barrel nut until it makes contact with the jamb nut
making sure the sling mount holes are facing the muzzle end and the holes for
the anti-rotation screws are at 3 and 9 O’clock.
(11) Align the forearm rail with the upper receiver, hold the forearm and tighten the
jamb nut very firmly against the forearm using our forearm wrench.
(12) Install and tighten the 2 anti-rotation screws. Use a low-strength thread locker if
desired
If you’re installing a forearm end cap YHM-9484A or B, follow the instructions
supplied for that product at this point of the installation. When finished installing the end
cap, return to step 12.
(13) Re-install the front sight being careful to align the gas tube through the barrel nut
and upper receiver.
(14) Re-install the tapered dowel pins being careful to install them in the proper
direction of the taper. Set pins firmly.
(15) Re-install the muzzle brake or flash hider to manufacturer’s specifications if
applicable.
Before test firing the firearm, be sure all components that were removed are
reinstalled and tightened correctly. It is recommended that you bench fire the
firearm first to be sure everything is operating smoothly. Always handle your
firearm with care being sure the muzzle is pointing in a safe direction and wear
approved shooting glasses and hearing protection when using your firearm.
Bookmarks