Okay, WRT brush, a high SD, heavy, round nose bullet does deflect less.
Jack O'Connor tried it with a lot of rounds, and he found that there is such thing as a "brushbuster" round.
He did find that the notion of "brushbusting" only works when you're shooting game that's standing in or immediately behind the bush, but that certainly is a valid pig-hunting scenario. Deflection with any bullet is too great if the game is farther behind the brush. However, if you're shooting at a pig in the bushes we have in California, a .45-70 will probably hit it, if you have a clear shot between you and the pig in the bushes, while a Spitzer will see more immediate deflection, according to O'Connor's tests. So some people use .45-70 and similar rounds to hunt pigs with.
Now, WRT the rounds, I was not clear. Yes, you can load a hot WinMag.
However, the increase in perceived recoil, which is significant since a standard .30-06 is just below the threshold that an average-sized man finds manageable with little effort, and a standard .300 WinMag is well above it, is only worth it if you need to have that extra energy at 400 yards, in my opinion (hence "never made sense
to me" -- that means I probably wouldn't buy one, and would choose other calibers, myself, like the .300 Wby, that's all).
Again, for factory ammo, .300 WinMag is twice the price. Recoil is notably nastier in a similar gun. But for sub-elk-sized game at 300 yards or less, the difference in effectiveness between the rounds in the real world is minimal.
It's all about choosing wisely, as opposed to buying into the "Magnum good, everything else bad!" myth that seems to exist, far more than any myth about any given cartridge, or what happens when you hit brush.
I was not trying to spread myths. Sorry if I did.
P.S. I stay away from fairy
tails altogether. And the fairies can stay the hell away from mine.