Deerhunter: you may not get the accuracy you want from a carbine. Unless you find one that is brand spanking absolutely, unquestionably, undeniably and without a doubt new, your accuracy may not be what you want. My sister got one a few yers ago that, for all intent and purposes, was brand new. The stock was perfect, the parkerizing untouched, the bore pristine. But even with new ammo it would not group better than 2 inches at 50 yds, which makes for 4" at 100 and 8 at 200. Maybe it was the ammo.
We used those things in Vietnam, for close range housecleaning. Unless we had a couple on the berms with us and knew that even if we missed the guy we were aiming at we might get the one next to him, we would opt in favor of either the M-16, the Car-15 or, my preference - the AK.
If you can find one and test fire it for accuracy with new ammo, and if it works and groups the way you want it to, go for it. If not, you won't be happy with the accuracy. What you must consider is that they have not been made for almost 40 years, and many of those left around or for sale have seen some extensive use. Go lightly when shopping for this mil-surp.
As a home defense weapon it is a fine choice. The round will penetrate through and through with ball ammo but it is easy enough to shoot for multiple shots. New PMC ammo with a 110 grain softpoint is a much better option. Hope this helps. Mikey.