Actually, although there were some civilian rifles made in Germany in 8X57J (7,8X57mm) with .318" bores, the military rifles (GEW 1888's) made for that round were actually .322"-.323" in the groove diameter and when Germany adopted the 154-grain, .323"Spitzegeschoss (pointed bullet) in 1905,many M88's were converted to fire this load. The conversion consisted merely of reaming the chamber throats larger so the cartridge case could release the .323" bullets. Nothing else was done to them. (As a fact, IF the cartridge case neck expands enough to freely release the bullet, it is conceivably possible to shoot almost any size of bullet through a smaller bore. The most extreme example of this I have heard of -in the American Rifleman-was of a guy who rechambered a 6.5mm Arisaka to .30/'06, but left the bore at .264". He was shooting .30/'06 ammo thru this barrel. Bullets were being swaged down to .264" to get out the muzzle!)

In other words, the very first rifles made to shoot the 7,8X57J round had bores of .322"-.323" to start with, and fired .318" bullets! I assume the original, heavy, round-nose .318" bullets depended on swaging up on firing to obturate the larger groove-diameter bores.

That's strange, since the .308 Win. was introduced by Winchester in their Model 70 Featherweight with the 1/12" twist as standard. The one I owned would shoot every weight bulletfrom 110 up to 220 grains with quite good accuracy. I loaded mine with the Hornady 220-grain round nose & 48 grains of Norma N205powder for a MV of 2300 FPS. This load was quite accurate from the 1/12" twist 22" Winchester barrel.