Congratulations Charlie, that is an incredible knife :thumbup:
I have long wondered about the tapering back springs, and the purpose of them. I spent long hours pondering the matter, and rooting through my old cutlery books, without turning up anything. I thought I'd asked Stan Shaw previously, but obviously not, or he'd misunderstood my previous enquiry, because he told me the answer straightaway. He said that in the days of the big Sheffield cutlery factories, a cutler would come into work, and there'd be a pile of hand-forged blades and springs already on his bench for him. However, the thickness of the springs varied, so they had to file them to the same width as the blades. The only place they have to be the same width is at the hinge though, and since they were all on stingy piece-work rates, and time was money, they'd taper the springs. I asked if that wouldn't mean that they then had to taper the covers. It would, said Stan, but it's a lot quicker to file wood or bone than steel.