The really old handles, used to have a thin catch, to hold the spear and whenever the spear twisted slightly, the gun would AD.
We drilled holes on the side, wher the spear went into the handle and put two thin stainless steel pins in the holes, so the spear was a really tight fit.
We made our own muzzles and I will try to find one to photograph.
I made a rail gun, by glueing two 3mm aluminium rods onto the barrel and filling it up with Eli fil, to make a rail.
The first rail guns, had the spear running inside the rail, with a litlle fin added on top of the spear, to locate the wishbone.
I still have a mould for making wishbones, out of cable.
It was a lack of money and an abundance of time, which made us devise all this sh1t.
I even built my own boat and the whole rig with brand new motors, cost me about R 13 000.
I sold it 16 years later, for R 15 000.