4140 machines nicely, will heat treat pretty easily, too. Gets plenty hard for this
application, easily available at many metal suppliers.
Agree totally with Keith. He points out a very important thing - it is very simplistic,
and in some ways, harmful to metals selection to use the term "stainless steel". The two
types behave very, very differently across the board in all things associated with making
things out of them. There needs to be, just like Keith said, two other critical divisions -
the heat treatable ones and the non-heat treatable ones. The austenitic SS act a bit like
brass - work hardens only, can soften with heat, but not harden with heating and quenching.
The martensitic stainless steels behave much like carbon steels, heat treat by quenching and
Relatively poor machining, and high cutter wear is a great reason for the home machinist to
avoid the SS alloys unless they are REALLY needed.