It may have been rechambered to 6.5 x 257 Rbts. Many were as the ammo for the 6.5 Jap was unavailable.
Do a chamber cast to see what it looks like. Simple candle wax is usable for this as no detailed information will be taken such as measurements.
Spray the chamber with silicone, put some cloth in the barrel just beyond the chamber and pour in the melted wax from the chamber end.
After the wax is hard push it out with a rod toward the chamber end .
