Great picture,Ralph...and a nice bird!....what kind of load are you stuffing down that fine double?
What I finally settled on for a good load in my vitage muzzleloader is, 1 1/4 oz, #7 nickel plated shot with equal volume of 2F blackpowder or 85 grains. Both barrels in my percussion gun I shoot are cylinder bored 12 ga .730 twist steel barrels. On top of the powder goes an 1/8 over powder card, a 1/2 cushion wad. A Ballistics Products BP12 shot cup, cut down to hold the 1 1/4oz of shot, and having four 5/8" slits, is dropped in the barrel and then shot poured in. An over shot card cut from an egg crate, with an old choke tube goes last.
The componets all have their purpose and work together to make a good killing pattern at 25yds max. Over powder wad acts as a gas seal. The cushion wad helps to seal gases too but also keeps the fire from melting the plastic shot cup. BP12 cups are low friction cups due to the 16 or so raised ribs on their exterior. You have to custom cut them to suit your needs. I still want to experiment with modifying the cups. You know you have gone to far when the cup does not separate from the shot in flight. My patterns are 26" wide at 25 yds. and when you are sighting down a plain rib of an old gun that is about right to get the job done.
Muzzle loading SxS guns are really versitile. You can load a plain lead ball with over shot card or patched ball and all sizes and types of buckshot and bird shot. The most important part of loading is consistency there are so many variables in the loading process.
Ralph