ALWAYS make sure that the firearms is unloaded, and the safety is engaged before performing any maintenance or modification of any firearm.
STEP 1: Remove the entire rear sight, shroud, and adjusting screws.
STEP 2: Measure the distance between the vertical ears of the receiver where the rear sight was mounted. The rear portion of the scope-base is machined to 1.090 wide. Due to dimensional variations between manufacturers, shims may be required to reduce the clearance between the ears, and the base.
STEP 3: Rotate the index-wheel of the base (2) or (3) full revolutions CLOCKWISE to keep from binding the elevation screw during installation.
STEP 4: Remove (2) 1/4 x 28 F.H.C.S. from the rear portion for the scope-base. Place the scope-base into position with shims (if needed) and re-install the 1/4 x 28 screws “FINGER TIGHT ONLY”.
STEP 5: Place the front rail support into position, making sure that the “key” at the bottom of the rail support is properly engaged with the slot in the left side of the receiver, and install (1) #12 x 32 bolt, “FINGER-TIGHT”, in the corresponding hole.
STEP 6: Rotate the index-wheel counter-clockwise until it stops at the, “0” stop.
STEP 7: Torque (2) 1/4 x 28 F.H.C.S. to 14ft. lbs. dry or 10ft. lbs. lubricated. Torque (1) #12 x 32 bold to 10ft. lbs. dry or 8ft. lbs. lubricated.
NOTE: if shims are used at the rear of the base, they should be equally on both sides to help keep the base centered.