I say give it a basic cleaning, with some Hoppes bore solvent to disolve the (likely) old dried oil, wipe it off, run a solvent patch through the bore and dry it, and go shoot it, with the old ammo. The ammo, if anything adverse, may be a bit weak, but is probably OK. Unless very old, like pre-war, I haven't seen old ammo go for all that much. A few price it high, but they don't seem to sell much of it, unless in brand new condition and certain types of boxes and ammo. I've bought many boxes, even a few pre-war, for less than new ammo.
It's a great old carbine, and should be fine, even if it takes a little TLC.
....Any surface protection would have been wicked off by all that stuff and you had this thing in an attic. Forget about it. It's probably long lost to corrosion.
2. Folks are recommending that you take it apart and clean it, oil it, etc. Don't take it apart unless you know, a lot, about how to disassemble and properly reassemble a model 94. It is NOT for beginners. It is very complicated. You can take it to a gunsmith to do the work, but if the outside is rusty, forget about it. Save yourself some time and money and junk it.
Wow! I guess my old 1927 made 94 carbine was junk when I got it and I never knew it. It was used hard on a ranch for likely all the years before I got it in the early 80's, and looked like it had never
been cleaned or cared for. It was rough, inside and out, but functioned fine, and shot decently for a pitted, neglected bore (about 3 1/2" @ 100 yds, and was a bit better after getting it recrowned).
I'd bet the 94 in the original post isn't bad, or it would have been mentioned. Give it a shine up, and see how it shoots. If the action has gummy old oil in it, a basic cleaning with Hoppes should loosen it up. I've found they rarely really need to ever be taken apart, though I had no trouble with the first one I got at 14 and couldn't wait to strip down and see how it all worked. Heck, it would be even easier with instructions.
My old neglected 94,