This definitely is not my area, but I've handled a lot of Japanese matchlocks over the years having seen them at Japanese sword shows. IMHO, this doesn't look Japanese or Chinese to me. It looks more Afganistan or one of the more Arabic regions. Also doesn't look authentically old, more like an aged tourista.
I could be totally wrong and off base, if so, just chalk it up to an old fart showing his ignorance.
Rich
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