My father, who hunted extensively believed there was very little if any differance. He prefers stepping up to a 375.
I agree with Ben's dad and probably came to the same conclusion about the same time...think we are about the same age.
I killed most of my elk with the 300 Weatherby and 300 Winchester, including some out to 450-500 yards. The 300 WM starting a 180 gr at over 3100 made those bulls go rubber legged. Some collapsed like they were dynamited.
The 338 is sort of a slugger,medium velocity medium bore cartridge. It give 250 gr bullets the same velocities a 375 H&H does with 270's. Good 250's are easily driven over 2900 fps from the 375 H&H and shoot as flat as any conventional 338 bullet. The 375 holds the same advantage in diameter/expanded frontal area over a 338 bore, as the 338 does over a 30 caliber, FWIW. I think it counts in favor of the 375 bore.Some may not agree.
On these same hunts I had companions with 338's and 340's shooting 210-225 partitions and I could really not see much difference between the 338's and the 300's on any bull elk fairly hit.
But Partitions are great equalizers among cartridges, the performance being so consistent caliber to caliber that terminal results can sometimes be hard to distinguish.
The "secret" as distances stretched was forget the lung shots and plant the shots on bone for more dramatic ,even if not always immediate), results. A bull elk that will shrug to a lung hit will likely not do it with a shoulder shot angled into the boiler room for maximum effect.
I came to prefer the high velocity of the 180-200 gr bullets from the 300's over the 338's. A light 375H&H filled in from there.
As to the mountain grizzly and the 300 Weatherby, my half assed view is the 300 Weatherby will make very short work of any grizzly. I had heard this but got to see it first hand on a good sized Alaskan brown bear killed by a companion. One 180 gr Partition from a 300 Weatherby killed him pretty instantly. There is no big bear I'd hesitate to shoot with a 300 Weatherby.
