Smith & Wesson Model 12 The Smith & Wesson ( S & W ) Model 12 is . 38 Special revolver on Smith & Wesson ' s K - frame ( medium size ) platform . It is an aluminium alloy - frame version of the Model 10 ( also known as the M & P ) . It was made from 1953 to 1986 in both two - and four - inch ( 102 mm ) barrel configurations . It weighs 19 oz ( 524 g ) unloaded . Early models used an aluminum cylinder as well as frame . Production Variants . In 1953 , the United States Air Force ( USAF ) ordered a variant of the S & W Military & Police Airweight with a two - inch barrel and aluminum cylinder to be issued to US Air Force flight crew members , called the " Revolver , Lightweight , Caliber . 38 Special , M13 " . Some 40 , 000 Smith & Wesson M13 revolvers were produced . After persistent reports on cylinder and frame failure with the M13 and its counterpart , the " Colt Aircrewman " , the Air Force attempted to remedy the issue by issuing a dedicated low - pressure . 38 cartridge for the weapons - the " Caliber . 38 , Ball , M41 " round . However , after continued negative reports , Air Force officials decided that the revolvers were not suitable for issue , and the model was withdrawn from service , all but a few examples being crushed or destroyed . A civilian model of the M13 was released in 1953 , called the Military & Police Airweight . This designation was changed in 1957 to the " Model 12 Airweight " . The Military & Police Airweight initially used both an aluminum cylinder and frame , and weighed only 14 . 5 ounces . The aluminum cylinder proved insufficiently strong to withstand continued firing with standard . 38 Special cartridges , and in 1954 , S & W changed over all new production Airweight revolver cylinders to steel , increasing the weight to 18 ounces . The Model 12 variants 12 - 1 , 12 - 2 , and 12 - 3 used a narrower hammer and had an aluminum grip frame that was narrower than the standard steel K - frame . The final version , the Model 12 - 4 , used the standard frame dimension of the other K - frames . It also featured a rounded butt . Pre - Model 12 - predates model number markings . It has an alloy cylinder and will be a 5 screw design with 4 sideplate screws and a screw in front of the trigger guard . Model 12 ( 1957 ) - 1 ( 1962 ) Change extractor rod to LH thread , eliminate screw in front of trigger guard - 2 ( 1962 ) Front sight changed from 1 / 10 " to 1 / 8 " - 3 ( 1977 ) Gas ring on yoke to cylinder - 4 ( 1984 ) Change frame thickness to same as all K frames Product development and usage . Since the Model 12 uses an alloy frame , it is not advisable to use + P ammunition since the frame may stretch during shooting . This is apparent when the primer s have elongated firing pin marks . Very early versions have aluminum cylinders and should not be fired . The two - inch barrel Model 12 is also called a " snub - nose " . Detectives and others with licenses to carry find the snub - nosed revolver , such as the vintage Model 12 , concealable , lighter in weight than its longer - barreled twins , and in an emergency , easy to deploy with its trim wood grips and round butt . It is also a proven performer as a back - up pistol for some officers , who carry a larger caliber pistol at their waist . The Model 12 is most often found to have some wear on its bluing due to age , but this wear does not detract from either its function or its value as a vintage concealed - carry piece . An important earmark is the factory stamp " Mod - 12 " on the frame inside the yoke . Also on the inside of the yoke is the revolver ' s serial number , which is repeated verbatim on the base of the butt . The Model 12 holds its market value nicely and is highly collectible . As with most older revolvers , a reputable gunsmith should check its functioning prior to purchase .