I quickly read through all the posts here and never saw anyone mention that the .300 Savage cartridge is the "father" of the .308 Winchester.
When the U.S. Army was looking for a replacement for the .30/06 in 1953-1954, they tested and picked the .300 Savage. But then, they began "playing" with the cartridge and increased the neck length, changed the .300's shoulder angle from 30º back to 20º for the .308 and, due to the longer neck, was able to make the cartridge body slightly longer while keeping the overall cartridge length almost the same.
The result was the 7.62x51 NATO cartridge which Winchester adopted and began loading under their own name (as is normal in the cartridge manufacturing business) as the ".308 Winchester" which has a sligthty larger case capacity than the .300 Savage.
However, a considerable amount of the higher muzzle velocity of the .308 vs. the .300 Savage comes from the higher pressure to which the .308 is loaded. The maximum pressure recommended by the SAAMI for the .300 Savage is just 4600 C.U.P. compared to a maximum chamber pressure of almost 5300 C.U.P. for the .308 Winchester. If the .300 Savage was loaded to the same pressure as the .308 Winchester cartridge, there would be little difference in the muzzle velocity out of the same length barrel.
As far as popularity goes, the .300 Savage, introduced by Arthur Savage in his Model 99 lever-action rifle in 1920 was the original short, fat cartridge designed by Newton to approximately the THEN muzzle velocity of the U.S. Army's .30/06 (a 150 grain bullet @ 2700 fps). Newton used a cut down .30/06 cartridge case to almost achieve this same muzzle velocity in the Model 99 Savage sporting rifle.
I was able to duplicate the 2700 fps original muzzle velocity which chronographed an average of 2707 fps muzzle velocity using a 150 grain bullet in front of 41.5 grains of some IMR4895 rifle powder made in 1995. However, I found that each subsequently newer 1 lb. can of IMR4895 I purchased yielded an ever-lowering muzzle velocity out of my 1953 Model 99 Savage with a 24 inch barrel. However, the factory loaded .300 Savage cartridges claimed to yield a muzzle velocity of 2635 fps which is still easily achieved by hand-loading. Some loading manuals claim up to 2700 fps with a 150 grain bullet out of a .300 Savage, but I firmly believe that would be a real "stretch". Besides, a 150 grain bullet out of a .300 Savage kills easily if the bullet is put into the game animal's vital parts.
The .300 Savage cartridge is still an excellent eastern deer hunting cartridge in it's 150 grain loading. Recoil is noticeably less than the .308 Winchester round and if sighted in 2½ inches high at 100 yards, it has a point-blank range of 250 yards meaning the bullet doesn't rise or fall more than 3 inches above or below the line-of-sight. This means, of course, that a hunter can hold "dead on" his target from the muzzle of his rifle out to 250 yards and not be concerned about "hold-over".
Any deer or elk struck by a bullet from a .300 Savage wouldn't be able to tell the difference between it and a bullet from a .308 Winchester... but that argument will go on forever. Shorten the range vey slightly... and the .300 Savage's bullet has the same ft/lbs of bullet energy as the same bullet out of a .308 Winchester.
That said... there is no doubt that when the .308 Winchester was introduced, it meant the "death" of the fine .300 Savage which reigned as "King" of the sporting .30 calibers (discounting the popularity of the .30/06) for over 30 years (1920-1955).
However, this "king" isn't dead... yet.
Strength & Honor...
Ron T.