This gas block replaces your existing front sight and allows the user to
mount accessories to its top picatinny rail while retaining the bayonet
lug and sling mount. This gas block allows the mounting of our forearms
without the removal of your muzzle accessory. Purchase our gas block
mounted flip front sight (YHM-9584) or our solid front sight (YHM-9495)
to retain your iron sights. Made from high quality steel and finished
with a Mil. Spec. phosphate coating. It is mounted by the use of four
socket head cap screws using a 7/64" Allen wrench. This gas block has a
bore diameter of .750 inches.