That's my fowler and a tree rat it plopped.
The question, "What is jugged?".....
So if you run an actual choke/constriction at the muzzle, it precludes shooting a round ball.
To shoot round balls, the muzzle can't be smaller than the nominal bore/caliber for the barrel.
As I understand the process of having a barrel jugged, the bore is opened slightly wider than bore/caliber. Then it comes back to the designated bore/caliber shortly before the muzzle. This allows a shot column to expand a bit, and be compressed right as it leaves the muzzle, which is supposed to tighten shot patterns.
Supposedly it's good for round ball accuracy, too. I can't argue with this gun's RB accuracy. Here's three off the bench at 50 yards, and the left one was the first after changing a patch lube.