Great stuff.

I consider my .358-similar, favored 9.3x57 a 200 yrd cartridge. I have killed elk and deer at that range with it and am quite comfortable with it at that range but no farther. I pretty regularly practice on game-size targets on my rifle range at 50, 100, 150 and 200 yards. I know what I can do and am confident of my shooting at those ranges from certain, practiced field positions. I would feel quite confident with the .358 at all those ranges, assuming proper bullets were used on appropriate game. I have shot enough game sized targets {and a few head of game animals} at ranges greater than 200 yards to know what my comfort level is, or isn't as the case may be. The .358 might be a 300 yard cartridge, but not in my hands.

If I were to take up with a .300 Mag, I'd consider it a 200 yard cartridge also, mostly because I am a 200 yard shooter!