i recently bought a colt series 80 gold cup national match,stainless with polished sides.it's a used gun with slight scuffing on the shiney part of the right side of the frame.i'give $592.00 tax included-deal or not.........if i swap from a 20"a2 upper to a 16"a2 what would the weight difference be.thinking about keeping my old upper and buying 16" that way i can have two rifles in one.....well thanks your friend pooh