What caliber and gun do you plan on using? Also what do YOU mean by "big game"? Lots of elephant were killed with pure lead round balls. Many Elk and bear were too. Buffalo were almost wiped out with bullets made from an alloy of around 1/20 (tin to lead) and shot from 50/70 and 45/70 guns. A hard cast bullet (20bhn+) can penetrate much more than a soft lead one. I use a straight Wheel weight alloy for some hunting and a slightly harder Lyman #2 alloy for other hunting chores. With a muzzle loader and round ball or conicals, I use a nearly pure lead bullet. It is difficult to handle soft lead with out damageing it. The UPS driver will throw it into the truck and on to your porch. SO, the bullet makers cast them out of linotype or harder alloys. YOU can cast them as soft as YOU like and handle them more carefully.