Brian, I'm going to be bullet testing with my 10 double this weekend at Birchwood. Not a 500, but at 11.5lb about the same weight and you definitely know it when it goes off. I've got a few smaller ones (all Brit, 1870's-1915) that you're welcome to handle to get an idea of what you want. If you're not too hung over from hashing pm me and come on out!

Bob