Perhaps the most effective elk killer I’ve had a great deal of experience with is the .270 Weatherby Magnum using 130-150 grain bullets. Barnes TTSX & TSX plus Nosler Partitions have been absolutely devastating on elk.
The second most effective elk killer I’ve used has been the 6.5x284 using 120 TTSX and 125 NPT. Again, impressive results on bulls out to a quarter mile.
I’ve also killed multiple bulls with both the .300 Wby shooting 180s and the .338 Win Mag shooting 210-250 premiums. Both the .270 Roy and 6.5x284 have been more impressive on elk than either.
Even though I have no direct experience with it, since the .264 Win Mag falls right between the .270 Wby and 6.5x284, I cannot imagine that it will be anything less than supremely effective for you. Find a 120-140 grain bullet that will hold up to its velocity and enjoy the DRTs.
