I looks like it used to be a large ring / intermediate length Mauser action.
But... there's no justifiable reason to chop the recoil lug off the bottom of a Mauser. And, that push-feed bolt doesn't fit the stereotype.
So... I don't know.
I'm thinking Type 38 Arisaka. ...with a LOT of work done to it.
"Such is the strange way that man works -- first he virtually destroys a species and then does everything in his power to restore it."