Any caliber with a base that is the same or very close to .30-06, so the bolt face slots will fit the rims. There are a number of other military calibers aside from the commonly used ones, 7.92 and 7.62X51, but they are generally not available or very practical. For instance 7.7 Jap, 7mm Mauser, 7.5 French, various 6 and 6.5mm rounds, etc. Hope this helps.
Black River Militaria CII