I have, along with the 6.5 Creedmoor and the 6.5x47 Lapua (which had been my 6.5 choice).
Nothing wrong with any of them - I just wanted “more” in the way of Bc.
Two ways to skin that Bc cat! Long and Light, or Long and Heavy!
I would imagine a .264 160 grain bullet would have an excellent Bc. I don’t know the exact twist for the old Swedish Mausers but I am sure it was very fast to stabilize those long bullets.
My own guess is the .260 Remington would be a perfect base for a standard military infantry cartridge. It would be deadly, very good at long range and has enough capacity to allow some pretty hot loads.
The greatest elephant hunter of them all, Walter Dalrymple Maitland Bell killed over 5000 elephants mostly using the little 6.5 X 54 Mannlicher (or was it 53mm long?) He also liked the heavy 160 grain bullets.