“Looks like 32 caliber is the closest analog to 7.92mm (.311 caliber)...” [kiryandil, post 76]
Original bullet diameter for 7.92x57 (aka 7.92mm Mauser, 8mm Mauser in US parlance) was 0.318 inch. The Gew-88 Commission Rifle (NOT a Mauser) and the Gew-98 were initially barreled for this diameter, firing a bullet of some 220 gr.
In 1905, the Imperial German military adopted a spitzer (pointed) bullet of 198 gr, later cut down to 154 gr in WW2 ammunition. Bullet diameter was increased to 0.323 inch; military rifles were supposed to be re-barreled. Many sporting rifles were never modified for the larger bullet; for many years, both sizes were available. One cannot count on every surplus military rifle to be equipped with the larger bore.
Never heard why the diameter was increased in military loadings.
I always learn something new when I go there, and it's always a pleasure.