Light guns are more difficult to shoot well. Light guns loaded up with late season pheasant loads, more so. Ive been involved in some late season pheasant hunting that was more like pass shooting ducks, but, honestly dont like that.
I havent looked real hard lately, but, if I see a 12 or 16 that meets your spec, Ill post it. I do not recall the gun you were bidding on. Sub 6 pounds is a bit of a tall order, even in a Darne. My 12 is 6 lbs, with its sling.

Best,
Ted