Yep, that looks like a 7.7 Jap to me, but the bolt is hacked up. Cross reference it to this sportered one (but don't buy it, as I am buying it next week, lol.)

http://www.williamlarkinmoore.com/product_details.asp?id=1680

The prewar ones were reknowned for their receiver strength, the late war ones were reknowned for their weak receivers. I would do a few pull string/vice shots before putting it to your shoulder. My grandfather hunted exclusively with a 7.7 Jap and made my uncle and father use them as well. I am planning on making two sporters out of two 7.7 Japs as we speak to give to them as gifts this year(and getting flamed bad at AR15.com for doing it too, funny reading http://www.ar15.com/forums/topic.html?b=6&f=14&t=233345&page=1)

Apparently Hornady makes a good hunting round for it, and the ballistics for the round are good.

www.cabelas.com/prod-1/0037464215974a.shtml