LB,what is the minimum SD that should be used for big game?
I would question why you're trying to achieve the minimum - "just how crappy a terminal performance can we get away with here?"
Weight retention also plays into it - weight that doesn't stick with the bullet doesn't count.
For stopping rifles for any sort of bear, I'd like to see SD=0.3 (mathematically illiterate grains/D/D/7000 method) and 90%+ weight retention across the full range of intended impact velocities. So in ..308 a 200gr Weldcore, Northfork, etc.
I would say the minimum for elk is SD=0.27 and typical weight retention of 70%+ across the full range of intended impact velocities. So in .308, a 180gr Partition, Hawk, Accubond etc.
For mule deer I'd say SD=0.22/70% retention. So in .308 a 150gr partition.
For whitetail, antelope etc. any big game bullet is probably fine.
