I chose 650 yds. Your 115 gr VLD is running at or above 2200 fps @ that range. The bullet will penetrate and will expand at that velocity.
For the record, an acquaintance of mine whom used to post here and was very well respected for his LR shooting/hunting emailed me the following a year or so back. His initials were GG and when it comes to this stuff, I'll accept his word as gospel.
"I have killed several spike elk with around 900 ft/lbs of energy. I have also taken the shoulder blades and hips of some of my cow elk and shot them at varying distances with different calibers. 800 ft/lbs broke them very easily. Of course, there was no hide on them and only a little meat.
I think I'd limit a big bull to 1000 ft/lbs, especially if he was in the rut. It would also boil down to where you hit them. I always shoot for the shoulder/spine area with the intent of smashing structure up. IF you believe in the heart/lung shot, much less energy is required. A friend of mine killed a bull on the Monroe last year with a 95 grain Berger VLD from a 243 improved at 850 yards. He hit it in the middle of the lungs and it blew them up like a bomb. Bull was chasing cows and filled up his lungs with blood very quickly and died within 50 yards.
Also, kinetic energy is only half the quation of terminal performance. You must also consider bullet construction. A Barnes x bullet and a Nosler Accubond could have identical kinetic energies but will have vastly different effects once inside the animal."
Just saying....
Alan