I was at a local gunshop this afternoon and they have a SKB 600 12 ga. sitting on their rack. Were there different grades to these guns? This one has no markings externally on the barrels, or when I removed the forearm, under them. The receiver has pretty much full coverage heavy scroll engraving and the only markings are CF735XX. It has some wear but is a pretty shotgun, they are asking about $450 for it, does this seem reasonable? Any idea when they were made?