Let's randomly select 100 hunters who shoot the .308 Winchester as their primary hunting rifle, and 100 hunters who shoot the .300 Winchester Mag as their primary hunting rifle, and put them in a side by side contest on the rifle range, shooting from kneeling and prone at 100, 200, 300, and 400 yards.
Anyone want to take any bets on which group would score the highest, by a very wide margin?
I have been shooting rifles from the bench and in the field for over 35 years, and have lots and lots and lots of experience seeing guys shoot their .300 Magnums in both instances. The vast majority of them are really terrible shots. Why? The .300 Magnums are just too much gun for the average shooter, and even for a very large percentage of experienced shooters. They encourage flinching, stock creeping and face turning in the large majority of people who shoot them. These cartridges are overkill for 95% of all practical hunting. Indeed, the vast majority of hunters I talk to who use them say they selected them "for knockdown power," instead of saying that they selected them so that they would have an adequate big game cartridge that they can easily use to precisely place a large caliber bullet exactly where they aim.
Now I know for a fact that there are some people out there who are exceptional, and can shoot the .300 Winchester Magnum very accurately and comfortably, at long range, short range, in the field, and from the bench. You are the extreme exception. And for this reason, I never recommend a .300 Magnum to someone who is looking for an all around rifle (especially focused on deer), or to someone who is just starting out.
Big Paulie