hello Colonel Custer,
100 $ is a bargain, 7x57 is a nice cartridge, smooth to shoot and generally accurate, with 162 or 175 grain bullets deadly for all north american species.
Have a sporter made on 98 mauser action.
Few years a go, I also bought a spanish mauser for $100 from a game warden, it is a .308 nato conversion of Oviedo with logo of Guardia Civil, the previous owner
removed the rear sights and drill and tap for scope base, I close the opening on the upper foreharm and set it up with a peep sights and it turn out very nice groups.
Buy it no regrets!!!