I have a '51 navy by Pietta that has a weakish mainspring. I've shimmed it way out and that was an improvement, but it will still not bust a cap every now and again. Does anybody sell a stout mainspring for these Piettas with some guts to it?
I have a '61 navy that had a weak mainspring and I shimmed that one out and that fixed the problem, but this '51 is going to need a bit more than a shim.