Your son's piece is not a Commander, but as the slide says a Combat Commander, the all steel version of the Commander. Starting in 1980 the 70 prefix was dropped and CCs were serial numbered 80BS1001 and by late 83 they had reached 80BS531218. From 79 to 83 the CC had it's own serial range numbers but were still series 70 guns. Series 80's guns started a year or two later if I remember right. Your sons piece will not have the lightening cuts in the slide as those stopped in the mid to late 70's. This is according to R.L. Wilson's "Colt an American Legend".