My money is on it being a arisaka type-99in 7.7 Jap.

The grind marks on the receiverand inletting of the ejector are a dead giveaway, not to mention the groove on the left side of the receiver, and odd ejection port shape.


edit: the timing marks on the barrel and reciver indicate the original barrel is still in place. The barrel should be chrome lined. There is also a chance that it might be a type-38 in 6.5x50, but from the looks of the parts, I'm pretty sure its a type-99.