Moisins have been rechamberd for 8mm Mauser by Poland, Germany and Austria, rechamber'd in 30-06 in America (Bannernmans are noted)
Into 6.5X54r, 9.5X54R, and quite a few .303 Enfeilds have been rechamber'd to 7.62X54r
Sometimes its just the barrel shank thats reduced and rechameberd, even in 7.62X54r (fix a bum or loose chamber)
You can rebarrels a Mosin into .410 shotgun , 45/70, ect. and quite a few other calibers, although not cost effective, it can be done by any competent gunsmith.
Good luck!