Very fascinating info , I've heard of the Ball Bags and I think you can buy repros.
I played around with loading 3, 6 and 12 pellets above and below the .648 round ball, the shot pretty much just sprays everywhere but one load "grouped" into a 3 shot cloverleaf at 25 yards, I think I had 12 pellets and a ball in that load.
A lot of the holes in the cardboard were already there so I can't tell which is the Buck
I carried the Buck in a leather shot flask and it was easy to just dump out a handful of buck . Could probably have dumped it right into the muzzle.
The pellets both above and below the ball seem to affect the accuracy of the big round ball, which makes sense since it will upset the flight of it either way. However, accuracy would seem like less of a concern if you're shooting at soldiers 80 yards away in volleys.
When I get the motivation I will load some Buck and Ball cartridges along with my normal Ball cartridges. I need to shoot at a bigger target next time so I can see where the Buck is hitting
I tried one load of about 20 buckshot and it just went all over the place even at 25 yards, half of it off the target backer but I wouldn't want to be on the receiving end of 20 .310 balls propelled by 100 gr of 2f