Several years ago, I bought a used Smith & Wesson Model 66-1 at a local pawn shop. It's got a 4" bbl, grooved trigger, square butt and recessed chambers but no bbl. pin. Have I got a "parts gun" or an anomaly?
it is most likely a transition gun, when they were phasing out the recessed cylinder and the pinned barrel, I have had a few like that. they wanted to use up the parts.