Model 642: .38 Centennial Airweight Stainless Caliber: .38 S&W Special.
Double-action-only revolver built on the round butt alloy J frame with three screws, 2" or 3" barrel, 5-shot fluted cylinder with a nominal length of 1.53", stainless steel barrel and cylinder. Uncle Mike's Boot Grips, 1/8" serrated ramp front sight with square notch rear sight, fully concealed hammer, .312" smooth combat trigger. Logo is found stamped on the frame and also laser etched on the sideplate on most examples. Produced 1990 – 1992.
Reintroduced in 1996 with the new J Magnum frame with three screws rated for +P as a hammerless Centennial with a slightly larger alloy frame and stainless steel cylinder. The firing pin was changed to a floating design; cylinder stop now machined into the frame. Frosted satin finish, "Airweight" laser engraved on the side plate with the S&W trademark found on the frame as well as the sideplate. Fitted with Uncle Mike's Boot Grips on a round butt frame, .312" smooth trigger, flat faced internal hammer, fixed sights, 5-shot fluted cylinder with a nominal length of 1.59". New shape MIM thumbpiece. Weight 15.8 oz.; 1.86" barrel (actual); cylinder opening is larger than its predecessors' at 1.345" x 1.732". Shipped in a blue plastic case. Master trigger locks shipped in fall of 1997. The LadySmith version is marked with "LadySmith" laser engraved on the side plate instead of "Airweight" and fitted with rosewood laminated grips from the Ace Grip Co., packaged in a "LadySmith"- marked softside zipper case. This is the first Airweight so marked in a LadySmith version. Mixed early production is also noted with MIM hammers and standard non-MIM triggers. Offered with Mag-Na-Porting by various distributors. Beginning serial number range reported as CNT0001 but not verified. Produced 1990 - 1992 and 1996 - date.
Supica, Jim; Nahas, Richard (2006-12-20). Standard Catalog of Smith & Wesson 3rd (Standard Catalog of Smith and Wesson) (p. 251). F+W Media, Inc.. Kindle Edition.