Tom,
Yes, I've a Coggie Cosmos and I'm embarrassed to say that I'm in a trough because, despite some major efforts to regulate, I cannot get both barrels to shoot together.
Velocity is in the vicinity of supersonic and, given the supermagnum experiences plus what I understand of Ross Seyfried's work with the Fauneta (20 bore Westley Richards), I wouldn't worry about that question.
Round ball did our ancestors well. But, choke rifled guns are a major improvement at the distances of hunting (as opposed to sniping).
Luck in your efforts!
Regards, Tim
