I guess we all have our own limitations. My limitation is up to the distance that the bullet will expand and penetrate and do significant damage to make a reasonably quick killing shot and ftlbs of energy really doesnt have a lot to do with it.
If I was hunting with a 308 and 165 SST's, I would take a shot on game as far as the bullet had sufficient velocity to open, period.
IMHO and it's JMO, a buulet that has sufficient velocity to open will have sufficient momentum to penetrate a deer. Now elk size game would be a different story. It would take a little more momentum to penetrate a 900 lb elk vs a 200 lb deer.
Most of us hunt with expandable bullets and not unexpandable solids. If we fire an expandable bullet tio a range where it wont expand, what's the point? (no pun intended
So I guess the bottom line is what is your criteria for a minimum killing shot on game at "X" number of yards?
Cheers and good hunting,