I have owned several 264 Win Mags over the years, and with today's powder selection, it is no slouch.
At one time, there were only 2 or 3 suitable powders for this zinger. Now we have at least 8.
In a 26" barrel, 3200+ is realistic with a 140 grain bullet.
This shoots mighty flat!!
I shot my Custom 264 at 100, 200, 300, 400 & 500 yards using the 140 Partition at 3260
Sighted in +3" at 100, it was just -16" at 500!
With this combo I shot Elk, Moose and q number of deer and Black Bear.
Don't remember shooting any animal twice.
The 264 is one chambering that did not deserve the lukewarm reception it got.
Regards, Eagleye.