I have one Pete. It is a C. F. Leader hammer gun with laminated barrels. I think it is from Birmingham around 1875. I assumed jug choking was done prior to modern choking but I now see there is a dual function to jug choking allowing a round ball to pass through for larger game while having choke for sporting clays (just kidding).

I have not shot it for years and I am pretty sure it is in the back of the safe so a pain to get to but I think it is marked "not for ball" which now makes no sense to me.

So many guns, so little time!