When a barely stabilized bullet strikes an object, animal or otherwise, it immediately becomes unstable. The results vary, from veering off from any 'stiff' medium, like tensed muscle, bone or sinew, or merely tumbling, which then results in much the same effect. Thus, the barely stable bullet cannot be trusted to carry through in a straight line. What this means to us as far as killing power, is that we might have a broadside shot at a moose, elk or bear, but the bullet turns on a rib, leg bone or spine and "upon striking a bone turns and courses through the soft parts of body instead of smashing those bones asunder creating a most grievous wound".
The reason for the story above, is that Winchester, in it's 'wisdom' rifled it lever action rifles similarly to the muzzle loaders of the say, ie: slow twists. Thus, the Winchester Rifles became "A laughing stock" on the Plains. They were known as rifles that "could not kill a buffalo". Mainly the problem was due to the slow twists and light weight slugs. They'd not travel in a straight line after impact and the light slugs lacked penetration. Thus, they turned, or tumbled. If turning, they missed the lungs, turning on a rib and running down into the guts- if they tumbled, they lacked penetration as a tumbling bullet stops quickly in tissue.
I am a very firm believer, that a person should learn to load and shoot a round ball in a muzzle loading rifle and that the round ball is the best projectile for killing North American Game from a round ball twist - ie: 48" and slower. I do not believe in trying to make a sub-small calibre 'better' by using a longer projectile. This does not make it more effective than a round ball in it's proper game range, but makes it a wounder of larger game for the reasons noted.
Deer are easily killed and the failure of straight line penetration and tumbling does not seem to be a detriment in them. In harder to kill species, please use an appropriate calibre and a round ball.
