Place the mount over the flange nut with the (2) 4-40 tapped holes toward the barrel end. Line the 4-40 holes in the mount up with the holes in the side of the receiver. It is very important that these holes line up to keep from damaging the threads when the screws are installed. Make sure the hole in the receiver hasn’t been damaged. The 4-40 screws should fit into the holes without any interference. Put in the (2) 4-40 socket head screws. Do not tighten!!!

Place a pin, drill, etc. through the countersunk hole in the top of the mount and into the hole in the special nut. Move the nut around with the pin until the round part of the nut slips into the counter-bore in the bottom of the mount. Put the 10-32 x 5/8 flat head screw through the mount and into the nut. Tighten this screw and the (2) 4-40 socket head screws. The 4-40 socket head screws don’t need to be real tight. Put the 10-32 x ½ set screw down through the tapped hole in the top of the mount and tighten against the receiver. The purpose of this setscrew is to keep pressure on the 4-40 button head screws.

If you are willing to remove some wood from the upper handguard you should be able to service the gas tube without removing the scope. At the area where the side 4-40 screws are, cut downward 3/32 to 1/8 & taper that down to nothing at the end of the wood in the rear. Do this on both sides.