I don't think you could reload on a lion or leopard charge even if the charge started from 150 yards out. They are just too fast.

However, most charges start at close range - well under 30 yards, so my personal opinion is that reloading is not an option.

There are cases where pumping lead into the body of a buffalo during a charge will slow him down or even cause him to stop and stand. At that point you could reload.