[hteas]

Jim,
It looks like it's rigged with no snubber. Instead the muzzle is attached with a nylon coated cable that has no stretch. The snubber is a section of surgical tubing with line coiled inside so that it will give some stretch (about 3X) when fighting a fish or missing and having the shaft hit the end of the line, and still be secured by the line running through it. When properly set up it allows a small amount of tension on the shooting line. If there is a dive shop you can get to, it would be a good idea to take it to them and see if they will help you get a snubber for it, and then shorten the shooting line.

And, at some point you will need a crimping tool, crimps, and some mono (200 or 250 pound-about 100 kg) to re-string the gun. Ocean oriented sport fishing stores will carry all of these. I restring my Rob Allen guns at least once each year, as the mono gets brittle with time.
Howard