Something simple.
I'm envisioning something "surplus" to use as a power supply and. I happen to have some at the manufacturing facility where I work, but they are all much too big for cartridge cases. We currently operate 6 induction heat treat machines for the production of band saw stock. We make our own inductors from copper tubing (they are all water cooled)as well.
I think that a simple inductor coil could be produced by many of the tinkerers we have on this board.
A secondhand Leco carbon determinator might just fit the bill. They are fairly common in the metals industry (foundries, steel mills, etc). If you could find one where the "determinator" part is broken, all you need is the power supply, the inductor, and a timer. You would probably still be into it for several hundred dollars though.
Lead bath quenching is fairly common in strip steel processing, but I wouldn't want to be the one to recommend that a private individual should use such a technique. Not that it doesn't work, only that there are safety and legal concerns.