Define "heat treating"
If someone dropped this in my lap, the first question I'd ask is what kind of metal is it made from - that is what chemistry is it? The chemistry determines what is feasible.
If metal is low carbon & alloy content, then case hardening is practical, which adds carbon to the surface and allows that portion to harden. You could nitride it too, but the hard layer is extremely thin, only .001" or so thick.
More modern action use low allow steels, which can be heat treated to though harden the metal sections.
