[miles]

Hiya

The most obvious solution is simply to fit new mono to the gun.

Another couple of options:
Fit a muzzle bungee to the gun.
If it already has a muzzle bungee, fit a longer one!!
If you have a clip or a muzzle bungee on, you could also use a thin peice of strong cord to lengthen the spearline.

What you must remember, as mono stretches, it'll lose its strength. Not critical if you're hunting 1-2kg fish, but it could well pop on bigger fish.

Rather just rerig your gun or take it to your local dive shop for them to rig it for you. Two crimps and some mono really costs very little!!

Regards
miles