Truth be told, you won't find the "ultimate" upland 16b gun for under $4k. That said, and given your paramater of a steady diet of Rem blacks and gp's, suggests to me that you should be thinking of a new AYA 4/53, AOC Uggie, or something similar. I just bought a new Uggie 16 and it fits your parameters exactly. Very lively balance/handling/light weight/straight stock and stout action/barrels capable of steady diets of hot factory ammo don't seem to be the domain of used guns, although I'm sure many will disagree with me.
Good luck!
