The American M1795 and French M1777 muskets were .69-cal.; the British Brown Bess was .75-cal.--17.5mm and 19mm wide, respectively. By comparison, the average assault rifle today fires a bullet with a diameter of 5.45mm (Soviet) or 5.56mm (NATO). This means that the wound surface area of a musket ball is truly massive. A modern rifle round will rely on its high speed and its tendency to start tumbling end over end inside your body in order to cause damage to blood vessels and vital organs; it might clip or bounce off of bones. A musket ball is more like a shotgun slug, and will bulldoze its way through with sheer weight. For comparison's sake, an M-4/M-16 fires a pointy bullet weighing 55 or 62 grains (0.13-0.14 oz) at supersonic speed, whereas a musket fires a round ball weighing something like 400-500 grains (0.9-1.1 oz) at high subsonic speed.