Gutting Sprague cans

[Jon A.]

I'm experimenting with a method of re-stuffing cans that doesn't mangle the crimp edge (much) and hopefully will make maintenance easy. Anyway, once I got the grounding rings and wafers out and removed some black material that came out in pieces, I ran into a really hard, black layer that I can't even melt, at least not without extreme heat. Am I going to have to heat them with a blowtorch or drill them, or is there some kind of trick to it?