great! i hunted 14 years with my last beagle, and every rabbit i shot over her was with my 20ga./62cal. flint trade gun. there is nothing like it. lots of smoke and fire. good for you! its nice seeing people carrying on the tradition. congratulations!
I use all but today was the 11ga.In the mid 1800's there was no standard like today.Every number ga imaginable was made.In Liege Belgium there were LOTS of gunmakers at that time.These are damascus,twisted steel,and laminated steel barrels.
As far as chokes there are several things can be done to tighten up patterns.I don't get caught up in it so I just use plain shot.I try to limit shots to around 20-25yds.
2)Over the powder card
3)Lubed fiber wad (some use and some don't)
5)Over the shot card
YES,it takes a while to reload!
Years ago they used wasp/hornet nests as wad materal.
The answers to all of life's questions are found in the Bible!