Curious as to the best gun trade you've made.
Doesn't usually work out for me. I'll start with a matched set of Purdeys and within 3 trades I've got myself a Mossberg 500.
I can relate to that!
Back in the early 80's, when Bishop semi-inletted wood was pretty cheap, I picked up an older 20ga Stevens sxs on which the receiver and barrels were good. Wood was still solid but pretty beat. Bought high grade Bishop stock and forend for it, which was a bit like putting more makeup on an old whore. Then I started having mechanical problems. Got them fixed, at least temporarily. Meanwhile, my buddy who had a Stevens 16 was lusting after my wood. So I swapped him the wood for a decent Remington 870, sold that, and likewise sold the Stevens 20 for more than I'd paid, with the original wood in place. Would not have been that big of a money pit in retrospect, but it looked that way to me back then, and I felt really lucky to come out ahead. My hunting buddy, with the restocked 16, tripped over some old barbed wire, fell on a rock, and shattered that nice Bishop wood.
