Before mounting handguard insure your receiver is mil-spec. If not, confirm fit of parts before beginning mounting instructions. Some non mil-spec receivers require barrel nut to be backed away from the upper receiver to allow clearance of over sized front lugs.
1) Once you have the old free float-tube and/or barrel nut removed, clean any grease or oil from the threads of the upper receiver extension.
2) This step is optional to allow easier installment of handguard. LocTite is not required for installation of handguard. Apply a drop or two of blue LocTite® to the receiver threads and screw on the large aluminum barrel-nut until it stops, then back it off until the gas tube holes line up.
3) Insert the barrel and slide the steel castle bolt over the barrel and thread it into the aluminum barrel-nut; now, use a .184” or 3/16” bit or punch to keep the gas tube holes aligned.
4) With the punch inserted in the gas tube holes turn the steel castle bolt by hand until you get a good, solid hand-tight alignment with the barrel-nut and receiver. Once you have the two aligned, let it set for a 2-24 hours. After the blue LocTite® has cured between the barrel-nut and receiver, the steel insert and barrel can be removed.
5) For final assembly, insert the barrel and thread the steel castle bolt into the barrel-nut until it is finger tight. Optional: (Then back it off three or four turns and place a drop of blue LocTite® on the threads of the steel insert where it is visible out of the barrel-nut).
6) Now torque the steel insert down to desired torque (according to your rifle manufacturer’s specifications). This can all be accomplished with or without the use of the punch but the barrel-nut can shift while you are torquing the steel castle nut, and it may need to be re-timed. We recommend using the punch to insure proper timing.
7) Once you have installed the gas tube, slide the handguard onto the barrel nut and align the 6 radial holes with the corresponding holes in the barrel-nut. Now the 6 countersunk screws can be installed. Tighten just until snug.DO NOT over tighten. Stripped screws are not covered by the warranty.
SLIM SERIES INSTALLATION
Before mounting handguard ensure your receiver is mil-spec. If not, confirm fit of parts before beginning mounting instructions.
1 ) Remove the gas tube, old barrel nut and barrel. Thoroughly clean the upper receiver extension threads. Apply a very thin coating of mil spec grease to the clean receiver threads. (note: apply only a thin amount of grease and small drop of blue loctite if desired)
2 ) Insert the barrel into the upper receiver. Slide the Slim Series barrel nut over the barrel. Thread onto the upper receiver threads and torque the barrel nut to 35 ft. lbs. Check gas tube alignment. If the gas tube channel does not align for the gas tube, then continue tightening the barrel nut until the next gas tube channel is aligned for the gas tube. Do not exceed a torque of 75 ft.lbs.
3 ) Once you have installed the gas tube and block, slide the handguard over the barrel and align the top rail with the receiver rail. Slide the handguard onto the barrel nut pushing firmly toward the receiver until it stops against the face of the receiver.
4 ) Alternately tighten the two 3/16 hex mounting bolts (with wrench provided) at the base of the handguard until a slightly snug fit is achieved. Confirm alignment of top rail with upper receiver, if needed remove handguard and adjust barrel nut for proper alignment. Once the handguard is properly aligned to the receiver and the bottom mounting hex bolts are slightly snugged, alternately tighten the four small 3/32 set screws (with second wrench provided) at the top and bottom of the handguard until snug. DO NOT over tighten. These set screws maintain alignment of the handguard while the bottom bolts are tightened, these set screws can also be used for minor adjustments to the alignment of the handguard in relation to the barrel. You will need to loosen the two mounting bolts slightly before making any further set screw adjustments, then re-tighten. DO NOT over tighten. Stripped screws are not covered by the warranty.