Daryl, This is a choke bored rifle, it was proved in the Birmingham Gun Barrel Proof House at 11 bore at the breach and 12 bore at the muzzles which should be .729, but when I drive a soft lead slug through it comes out at .775.
I just re cast my balls to 50% wheel weight and 50% pure lead as per your previous suggestion.
The Kynoch cases I have are new unfired but are Berdan primed, I still need to figure out a better primer system I agree with Tinker, it is worrisome.