No, I've looked everywhere for any indication of the bullet type, weight, etc., but don't see any of the usual markings you mentioned. Does the timeframe of manufacture provided by ellenbr give any clues?
I don't believe I have a hole gauge. And I'm working on this project with seriously limited funds. Right now, Steve's offer to double my money on the gun would be the "responsible" thing to do... but then I wouldn't have the Drilling I've been dreaming of for the past decade.
So, what kind of math are you talking about? How do I find the appropriate bullet size to use?