Once the Handguard is slid into position the cutout in the barrel nut should be visible in the window of the Handguard as shown here.
The square “block” on the QD Sling Mount will fit into the window of the Handguard and “lock” into the barrel nut. While holding the block forward against the barrel nut, the two Screws are then tightened on the QD Sling Mount block to 15 inch-pounds. This process must be followed on both the right and left side of the firearm.
CLEANING FIREARMS, OR HANDLING AMMUNITION MAY RESULT IN EXPOSURE TO LEAD AND OTHER SUBSTANCES KNOWN TO CAUSE BIRTH DEFECTS, REPRODUCTIVE HARM, AND OTHER SERIOUS PHYSICAL INJURY. MAINTAIN ADEQUATE VENTILATION AT ALL TIMES. WASH HANDS THOROUGHLY AFTER EXPOSURE. SHOOTING OR CLEANING FIREARMS MAY EXPOSE YOU TO LEAD.