I would not go out hunting deer with a 9mm.
The JR carbine is also available in .40 and .45., which are more powerful than the 9mm.
The bad thing is the JR is blowback operated, and set up for standard loads, so forget hot handloading some 250 grain bullets into a 45 acp case, which would be a totally different story than factory 9mm. The JR carbines can't handle any hot loads at all from what I've read.
I would agree with others that if the OP wants a handy little carbine in a pistol cal, find something like a Win 94 trapper in .44 mag or 45 colt and then handload it and you're perfectly fine.