Thanks for the info. I bought some mixed vintage ammo at the gun show; most of a box of Western with copper plated bullets. It was solid head though...... however, in the mix, were six really old, "balloon head", rounds. If new primers will fit in them I will reload them with Dupont fffg and hope I can get the proverbial 40 grains in them. So far, I've only been able to get 31.5 grains of Gearhart-Owens fffg in my solid head cases. If it works well, I'll be asking around for more '"ballon-head" cases. I expect they will be hard to find as I've never encountered them before. After many years of, "bad press", I never thought I'd see the day where they might be more desireable than solid heads; but right now, I'm thinking that they well be advantageous with black powder to get maximum velocity. What do you think?