I have a 30-06 with a 22 inch barrel. I tried out the Federal Hi-Energy 30-06 rounds, in 180 grain bullet weight, that were advertised to give speed and energy in the same class as the 300 H & H Magnum.
I fired 20 shots, using a chronograph. Guess what. It was true!!! On average, the rounds were within 20 feet per second of the published factory velocity of the 300 H&H Magnum 180 grain loads coming out of a 22 inch barrel.
This is another reason for never buying a magnum. If you need that little bit of extra reach some day, just buy the Hornaday Light Magnums, or Federal Hi-Energy rounds, and you've got a 300 H& H.
The 300 H&H was long regarded as a super big game round. With 180 grains Barnes X bullets or Swift A frame in the factory ammo, there is no Elk, Moose, or Grizzly that I wouldn't shoot. (Kodiak Bears, maybe not, but if I had $25,000 to hunt one, then I would also have enough to buy a special gun (.338 Win Mag) for that single hunt. Never going to happen.)
The later .300 Winchester only gives you about 200 feet per second more. No big deal.
The vast majority of the guys who are advising against buying a Magnum are, like me, people who lived through the Magnum Mania years of 1965 to 1985, when we were all hypnotized by mass marketing to believe that you simply were not properly equipped unless you had a magnum. First the .264 Winchester Mag, then the 7mm Rem. Mag, then the 300 Winchester Mag, and on and on and on. Guess what, after forty years of hunting, and after wasting TONS of money, we found out that in the vast majority of cases, they are absolutely and totally unnecessary. They are also no fun to shoot, and they create more problems than benefits. In our old ages, we found that when we really wanted to go hunting and kill some game, up through Moose, we reached for the old .30-06, .308, .270 , or .280, because these worked totally fine!
Maybe we had to get within 250 yards instead of 275 yards, but that's why they call it "hunting."
Looking back, I think that the first prominent gun writer who turned against the Magnum Craze, was Jim Carmichael, in the early 1980s, who started writing extensively about the killing power and efficiency of the .280 Remington, and demonstrated that for all practical purposes, it had the same killing power as the 7mm Rem. Mag, out to the longest practical distance that you could shoot, without the big recoil, ear-shattering noise, and other negatives of the magnum.
Best Regards,
Big Paulie