Type 38 markings question

[Guamsst]

My wife, a Japanese speaker says the sling markings, read right to left in the picture looks like the numbers 3870. She agrees that the wood stamping is Chinese.

Unless she is in her 80s there is little chance she can read more than the most basic Kanji from pre 1946, That does not though mean the stock mark isn't Chinese. There are plenty of reasonable ways for the Chinese to have marked this stock.