I have used 0-1 for decades. It is easy to work and uniform in dimensions. Tumblers I make are 1144.a material that machines as easy as 12L14 and oil hardens like 0-1. I can't even visualize making any lock parts from car or truck springs. There used to be a man in Pennsylvania that made tumblers from torsion bars taken from Chryslers and Packards and mainsprings he made from half hard 1095. Hw went out of his way to figureout the hard way to do really simple jobs.
Bob Roller