Here is the original rig that I used to use. At the time I was fishing the Valley waters a lot and the "helicopter"rig was the in thing for long range work.
I was disturbed by the number of "crack offs" and "cut offs" people were getting. All the other rigs would not allow the shock leader knot or the lead core splice to pass through them. After a lot of messing about, me and my mates came up with this idea. A lot of the lads put a lot of effort into making this safe rig work.
Certainly dated now, but I honestly believe that it is still the only rig of its type that will leave just the hook, hook link and swivel in the fish. All the others seem to just dump the lead.