LOL, at what point in the death of the deer did the bullet fail?
And as far as the bullets I use, yes I use the Aerotip and it works fine. Your post above slammed Powerbelts, not Aerolites.
If you use a light bullet, and push it too fast, you get what you deserve (In your case a dead deer). I've killed several Mulies with 348 Aerotips, and not one stopped the bullet.
It ain't rocket science, and open-sighted muzzleloaders don't need to shoot light bullets at high velocities.