NEF Single shot .223, Under $200 at walmart, Winchester sells a 40rnd box of .223 right now that goes for under what most 20rnd boxes sell for. Either that, or you're looking at something SEVERELY USED. I'm pretty certain NEF puts out a heavy bbl version too, at least they do in the Handi-rifle...I can't promise the heavy bbl handi rifle is under $300, but I'm pretty certain it is!!!

BTW, NEF is the same thing as H&R.