jaz : Thank you for the info ,yes 3in chamber ,it may have been a Nitro gun from the start as there are no marks to say other wise & it only has modern Nitro repoof marks !
I suppose if I had some BP I could have filled the vintage brass cases that came with to see what they held with a card & ball ?
Seems a little heavy for a 7 dram gun ??
Unless the guy was a poof ?

Thanks again !