K20 Smith & Wesson K Frame Model 12 4" Barrel Blue Used 38 Special Airweight j42n This complete assembly includes the

This complete assembly includes the hammer and stirrup

Type: Oversized

About the Model 18

Model 640 -

This is from the Jerry Miculek Performance Center version

K20 Smith & Wesson K Frame Model 12 4" Barrel Blue Used 38 Special Airweight j42n This complete assembly includes theK20 Smith & Wesson K Frame Model 12 4" Barrel Blue Used 38 Special Airweight Please call or email with any questions! How to determine the model number of your Smith & Wesson Revolver. Swing out the cylinder , check behind the yoke on the frame for a MODEL NUMBER. Model numbers began in 1957 58. So if there is no model number then your revolver may be older than 1957 58. In this case we can possibly still find the part you need with the serial # . If