I only traded or sold 2 guns in my life and I regret both of them! Around 1969 I let my brother talk me into trading him my 3-screw Ruger Blackhawk .357mag for his pump shotgun. Not sure what happened to the shotgun but that Ruger was missed almost immediately!
I let a friend talk me into selling him my Factory bright nickel Colt MKlV Series 70 1911 I had bought brand new for $170.00 in about 1974! I, foolishly, thought I wanted a blued one instead. My brother let the replacement blued Series 70 rust and pit terribly when I loaned him the gun and forgot to get it back from him for about 6 months! I made him buy me another one to replace that one and, by then, the Series 80 had been introduced and it was a 1982 model. I still have it. All stock and pristine but the box and docs are long gone!