Joseph DeMartino
Senior HTF Member
Why don't you try it and let us know? Or have your next-of-kin do so?
Best guess is the brass would cause arcing, which could eventually set off the main powder charge. I'm not sure if the heat/electricity from the spark hitting the outside of the case would be able to set off the primer in a standard round. (I know that some very rapid-fire weapons, like the Vulcan mini-gun, use electrical firing systems, but I think they also use special primers to work with them.)
Either way, I think you'd be buying a new microwave, at the very least.
Regards,
Joe