RE: good double barrel for under 600
I think there are some fairly recent imports from Russa that are pretty good looking. Name starts with a Bai something. Friend of mine in Waco bought an O/U 20. He loves it and got a good deal. Like under $400.00.
I havge a old Fox/Savage 16 side by side that is pretty neat. I want a side by side 410. I have seen a lot of side by side 20s in gun/pawn shops. Mostly savage for under $300.00 or so.
Not sure what your looking for. The 3 Bs Benneli Browning and Beretta are gonna be high.