All gun places I've been have seen dwindling used racks.
I think Joe gun owner is seeing the writing on the wall and much less willing to give something up these days - better off simply saving another month or two and buying it outright, no trade so you have 2 guns, not 1. So to speak.
I've seen the same. Think guys are also hesitant to trade because 'they don't make 'em like that anymore' is accelerating rapidly under the $1000 price point. Hard to get raped on trade and swallow the price tag on a new pick your poison.
