There are a few points that have been brought up since I last posted that I would like to comment on.
The first is a the over-kill of a .375 bore rifle. The .375 in its various guises is designed for very big game, and it's bullets, at least the ones which weigh 270 grs or more, are designed for reliable expansion and deep penetration on heavy dense targets. When one of these bullets impacts a 100 pound game animal, like an impala in Tanzania, a black tail in the Queen Charlottes, or a speed goat in southern Alberta, the result is a bullet that exits after moderate expansion leaving a dollar sized exit, a sufficient, though not the excessive wound volume, common to the high velocity small bores, allowing one to "eat right up to the bullet hole." The versatility of the .375 loaded with a single bullet weight is simply unchallenged. By contrast, the versatility of a .30/06 or a .300 magnum is due to the selection of bullet styles and weights available in .308". While a big case .416 like the Rigby comes very close, it cannot do what the .375 does with the same level of recoil. I could comfortably fire 5 rounds from prone with full powered 350 gr loads in my .375 Ultra, but only 3 from the .416 Rigby loaded to drive a 350 at 2850. To get 5 Rigby rounds to stay on target was more than difficult, and I tended to have less finesse on the trigger after the first 3 if I couldn't/wouldn't take a break.
The next issue concerns the idea that one is able to take game with a .300 magnum that cannot be taken with a .30/06. The problem here is that the faster bullet from the .300 upon reaching the target is still the same bullet that leaves the muzzle of a .30/06. Thus the wound volume and and depth of penetration is essentially unchanged, the difference is that the .300 magnum can do it farther away. The funny thing is, at very close range, when loaded with similar bullets, the '06 might penetrate deeper than the .300 as the violence experienced by the bullet on impact is not as great, so expansion takes place over a longer period of time, so the result is a smaller frontal area that is less resistant to penetration, fir a greater period of time. Thus in some circumstances, the 06 might penetrate deeper and be a better killer on a bigger animal. The various .300 magnum cartridges are wonderful for stretching the range be it in the game fields or on the rifle range, but if you find yourself in a hunting scenario where the power of the .30/06 might be lacking, going bigger is preferable to going faster. Many move to the .338 or a .358, but my next step from .30 tends to be a .375, as bullet weights commonly available in the .338"s and .358"s are also available in .308". If someone wants to make an argument for a 9.3X62 a 286 gr bullet at 2400 fps doesn't leave much room for complaint amongst the enlightened. Neither is the .300 magnum the rifle for a once a year shooter/hunter. Some occasional shooters have trouble with full powered loads in a light weight .30/06 rifles. The only way to build up and maintain tolerance to powerful rifles is to shoot them frequently, and working the off season with an AR-15 doesn't do that.
So what is the difference between a .308 and a .30/06? The short answer is that there's not that much difference. Both will push a 150 gr bullet to 3000 fps from 24" barrels, and when Stuart Edward White made his foray to Africa a century ago, he did it armed with the then new .30/06 chambered in a custom 1903 Wundhammer 1903 Springfield loaded with FMJ 150 gr ammo loaded to the unheard of velocity of 2700 fps (that was the only load available) though he was able to work up some 220 gr loads some time later. This 150 gr load successfully accounted for dozens of head of game over several months in the hands of this phenomenal marksman, and he compared the performance favorably to the .405 Winchester. No game animal shot with the .30/06 was lost, thus began the storied prowess of one of the most successful game cartridges of all time. Since that time the performance of the cartridge has been improved due to advances in propellants and bullets, and the introduction of the .308 allowed this level of performance to be realized in a smaller handier rifle. Where the .308 has a disadvantage to the .30/06 is when bullets heavier than 180 grs are chosen, as the velocity possible with slow burning powders in the .30/06 are unavailable to the small powder capacity of the .308. Conversely, the advantage in trajectory a .300 magnum has over the .30/06 can only be exploited by a relatively few field marksmen; thus to my way of thinking, both he .308 and the .300 magnums take a back seat to the .30/06 as a big game hunting cartridge.
