The rear screw actually has an oversized washer to create a lip to trap the mono, and a steel sleeve to cover the threads. The parts can be had from SS, you can contact them through their web site at
http://www.slinginsteel.com/ or just make something up at the hardware store.
From the installation instructions:
The front catch screw is a #6 x 3/4 inch truss head screw.
The rear is a #6 x 1 inch truss head with chrome sleeve/finishing washer.
On the bottom front of the handle assembly you will find one or 2 screws that attach it to the barrel. Find the front one. Measure 2 1/2 inches towards the muzzle and mark the center of the bottom of the barrel. This is where the rear screw goes. Drill a 3/32" pilot hole and drive the screw in until the sleeve touches the wood. (the sleeve is 3/8" long).
For the front screw, unclip it from the spear. Start at the muzzle & wrap it around the rear screw back to the muzzle until you reach the last wrap. Gently pull the end towards the handle. Mark the barrel in the center at the end of the snap swivel. Drill a 3/32" pilot hole & install the other screw. Stop with the head about 1/8" from the stock.
Remove both screws and thoroughly seal the inside of the holes with polyurethane, nail polish or something similar. Then reinstall the screws.