Were those the ones with the nickel jacketed bullet? Someone gave me some WWII vintage 9MM once and I decided to try it in a pistol. I only fired two and the second was only to see if the first was a fluke.
No idea. Like I said, it was Very Long Ago, say, 1957ish, and I was barely tall enough to see the top of the shooting bench. I was used to gun fire, even then, I remember these as being exceptionally loud and painful, even from 60 years on...