Bishop, I'm not really surprized by that, S&W has an extensive history of releasing oddballs assembled using whatever stock was at hand. However, 4 inch 610-3's were supposed to feature unfluted cylinders and the 6 1/2 inch version got the fluted cylinders. Personally, I would have just loved to have stumbled on a 4 inch 610 with a fluted cylinder, to me the unfluted cylinders look unfinished.