Confirm Type 38 original

Hi all, I recently inherited a sporterized type 38. When I hunted with it as a kid my Dad and Grandfather just referred to it as "the Jap" rifle but never shared particular ammo. I believe it is still chambered to 6.5x50. I don't see marking to indicate a .257 or similar on the barrel. Short of having the gun slugged or cast is it possible to make a reasonable determination that the gun is indeed a 6.5x50 based on the markings and serial numbers? The serial number is 51451 and I've attached a pic of the markings.

Attachment 82036Attachment 82036

All Type 38's as made were 6x5. What someone converted them into after the war is not going to show up in any markings unless they themselves stamped a new chambering on it. Odds are, it is still in the original caliber but you should check to make sure.

The popular conversion was to 6.5x57mm or 6.5mm/ .257 Roberts . The rifle still had the original 6.5mm barrel , just the chamber reamed longer to let you use .257 Roberts brass with a .6.5mm bullet in it . It was not meant to shoot .257 Roberts [ other than to fire form the brass ] as the .257 dia bullet in a .266 dia groove would have poor accuracy . If your rifle will CHAMBER a .257 Roberts cartridge , it was rechambered . If it will not it should be 6.5x50 Japanese . Even if you fire a 6.5mm J in it and it IS 6.5mm /.257, it will not really hurt anything .

Thanks for the quick replies. I took out the bolt today and found what looks like another piece of evidence. The bolt itself seems to be hand stamped with .260. I assume likely the same thing as .257/6.5? Now to get the bolt back in, kinda fun to re-learn the gun that I used as a 12 y.o.

Attachment 82141

That's the assembly number. Probably find it on other bolt parts and if you are lucky the rest of the rifle. It is different than the serial number on early rifles.