How much do you practice running shots at 70 yards with that rig? My bet is you never have so you have no idea how much lead is required. Muzzleloaders all have a "lock" time where it takes a bit for the powder to ignite plus they fire a heavier bullet at slower speeds than a centerfire rifle. Frankly in my opinion that is a shot you should not have taken. The game deserves better than being gut shot.