I'd steer away from the Nosler Ballistic Tip. They are designed to function properly at non-magnum velocities, and are known for being a bit on the weak (read: frangiable) side even at those speeds. I'd think that there's just too much chance the BT out of a magnum would turn into little more than a glorified varmint bullet at such high speeds, especially if the range gets close
I have taken 8 elk and 2 moose with the 180gr ballistic tip out of my 300 ultramags.No bullet failures to date and only one bullet recovered.That one passed through both shoulders of an elk and lodged in the hide.The 300win mag produces less velocity than the 300ultramag and no deer is even close to the size of a mature elk or moose.I use the 140gr ballistic tip out of my 7mmstw's for all of my deer hunting and with over 20 deer killed with this combination,there have been no bullet failures.Like the ultramag the velocity is much higher than the average cartridge.