Sounds like a great find...have you fired it yet ? My late father, gave me his WWII M1 Carbine when I turned 18..I'm now 45. I use to be in such awe of that gun as a kid.
My brother and I took it out for some target shooting today..put about 120 rounds thru it...jammed about 10 times..not bad for that many rounds. Jams for the most part with those rifles, have a lot to do with the cartridges being somewhat under loaded. I keep this Rifle in top working condition with precise cleaning after each use. We shot from a distance of 30yds from a standing position...at one point, I was able to actually hit the bull and follow up with a shot just below the bull..see attach pic
I took a very short Video from my phone...my brother nails the target a 10sec and 30sec into the clip.
http://www.youtube.com/watch?v=BxYr2Fs66cA