300 ultra-magnum
Dear Shooter:
Why on Earth would a person want an "ultra-magnum" in a NEF?
We are so over-powered in this country it's not funny! With the "good old" 30-06 you could slay any dinosaur that ever walked the earth - and in an NEF single shot - as the gentleman said, "your shoulder!"
I'm not trying to deride your idea but there is no reason for it.
The word "magnum" started with the British straight walled cases that needed a belt to headspace on; now, these abortions they call "short magnums" try to do the same thing as the (if there really are any) standard calibers!
I have real problems with the super-short cases with the bullet clear down in the powder space. Years ago when you said "300" it meant the 300 Savage! Now, while the Savage killed everything that walked (along with careful shots from a Win. 73 in 44-40) our new cartridges, in my opinion are just excuses for poor range estimation, and the feeling that it shoots "flatter."
No gun shoots "flat" for any distance, period!
Harry B.
P.S.
Shooter, get a CZ rifle in 375, or 416 Rigby or 458 Lott, then you've got a real magnum.