Back in the dark ages S&W used to make long barrel forgings and then cut them to shorter lengths when needed. Then the front sight ramp was attached to the rib via. a slot and pin. If you look closly you can see the pin(s) in the rib. Six-and-one-half barrels as well as others were made in this way. Later they changed to making the barrel forgings in 4, 6, and 8 3/8 inch lengths with the front sight ramp part of the forging, and pined the blade to the ramp. Now get out those model 27's and 28's and look-see ... 
