Am I missing something here? The original pre-1924 Mannlicher-Schoenauers were not produced in 7x57 Mauser caliber. If it is that caliber, it was already modified at sometime in the past. I only remember 6.5x54, 9x56, 8x56, and 9.5x57 MS calibers in those early guns. From several articles in the Mannlicher Collectors newsletters, the rotary magazine MUST be modified if the caliber is changed. Even then, the success of the modification is iffy.