S&W started using sleeved barrels 20 to 25 years ago. They have used sleeved barrels on all of their frame sizes. Many aluminum framed models obviously got aluminum barrel sleeves to reduce gun weight. Examples are K, L, and N frame Night Guard models, Model 329 .44 Magnum, Model 357 .41 Magnum and Model 325 .45 ACP N frames and .38, .357 and .44 Special L frames. In addition to the more numerous all stainless steel sleeved barrel K frames there were all stainless steel sleeved barrel Model 629 .44 Magnums, Model 520 and Model 519 .357 L frames and Model 60 J frames. It would take a long time to put together a complete list. If you narrow it down to the model that interests you then we could look it up for you. For example Starting with the dash 5 all Model 66s have had sleeved barrels. All earlier dashes had one piece barrels.