Back a few years ago (about 30
) I had a 300 Win Mag, a 300 Weatherby, and a 300 H&H, all at the same time and all M70 Winchesters. The 300 Win and Weatherby were custom and the H&H was a stock pre 64 M70. I was in my 300 magnum phase learning my way around these cartridges, and I took the Weatherby and Winchester hunting quite a bit. I loaded a bunch of bullets but mostly 180's in all three.
The fastest of the three was the Weatherby which averaged about 3150 from a 24" barrel; the 300 H&H did 3090,and the Winchester was sort of stuck somewhere in the middle of those two. The results sort of surprised me because I had read from various sources that the H&H was no better than the 30/06 ballistically, and the 300 Weatherby was the barn burner high velocity king of the 300 magnum crowd.
But I had never seen a 30/06 do any better than 2750-2800 fps with sane loads. The H&H was close to 300 fps better,and fell behind the Weatherby by a whole 60-70 fps (!) Later on I would learn that, if you outfitted the Weatherby with a 26" barrel and the right powder you would get over 3200 fps with a 180 gr bullet.But I chronographed Weatherby factory ammo with the 180 and it did 3190....not bad,and about 100 fps faster than the H&H with good handloads.......again this ain't what I had read.
I also learned that, if I loaded the 300 Win Mag in a H&H length action and OAL to 3.5+", it would rival the Weatherby for velocity...and in a 24" barrel, so seemed more efficient,I settled for 3150 or so with a 180 gr bullet and used that load for a lot of hunting.Powder charges were 8-10 gr less than the Weatherby,depending on the powder.
Had a bunch of other rifles (factory and custom)chambered for all three cartridges and results were always much the same.
I concluded a few things....first, my old mentor, JOC, was right about a lot of stuff but dead wrong about the H&H vs the 30/06...the old Holland round stomps it with good handloads,even if the factory stuff is nothing to write home about....but that can be said of the 30/06,too with some factory ammo.
Second, while it's good with anything the "best shot" for the 300 Weatherby was with a 26" barrel, and a 200 gr bullet at close to 3100 fps. This is where the bigger case showed some superiority over the smaller one's.
I owned a 300 RUM when it came out,and have sat and watched load development in rifles belonging to friends;shot their rifles quite a bit. It's easily the fastest but I could not fall in love with burning 90+ gr of powder and torching it all off in an 8 pound mountain weight rifle.I'll leave that to others.
I hunted with the H&H, Winchester, and Weatherby, killed a bunch of elk and other animals with the Winchester and Weatherby from hard off the muzzle to 400-500 yards.I found all three to have more punch on heavier animals like elk on the far side of a canyon than a 30/06, which is no toy,but isn't a 30 cal magnum either.
I sort of learned that the velocity differences between the first three cartridges were not really the quantum leaps I had been led to expect, but more like baby steps between all three. What I could do with one I could do with the others,at the range and on game.
So these days when someone asks about "which 300 magnum?" I shrug because once you start a 180 gr bullet at around 3100+- fps it doesn't matter;and at least with these three cartridges there's only 100-150 fps that separates them.
I never used the real heavy match bullets in the 300's but maybe the differences will matter more with those bullets.
