If it will shoot like that at 50yds, it shoud be good at 75 & 100 yds for deer hunting. That barrel is shooting roundballs better than 90 % of them will in that twist.
Triple Seven, adding a card wad or any wad between the powder and patched ball sure adds pressure to the barrel. A good tight patch and ball combination should be sufficient. It is easier to load also in a pinch.
Good luck on your hunt Flatlander.
I got my .55 cal flinter w/42" barrel out and shot a couple through it. It is always the same, with fixed sights. 90grn fff Goex, .025 patch and .540 pure cast ball. The load has to be hammered in but I have never had to shoot a second round. I do carry a couple of speed loaders with thinner patch for a second shot, just in case.
Mike