Looks like it could be a duffel-cut. Many GI's cut the stock under the barrel band so that it would be short enough to fit in their duffel bag for the trip home after the war. The stock could be re-assembled and the cut wouldn't show under the band. The handguard and remainder of the stock on this one is missing and the band has been moved back.
Does the number on the bolt match the last digits of the serial number? If not, you may want to have it checked for headspace.
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Markings on Japanese Arisaka Rifles and Bayonets of World War II