what is the difference in muzzle velocity out of a 2'' barrel and a 4'' barrel for a .357 magnum? 10 feet per second?
'pends on the load. In my guns, and typical experiences as far as I've read, the same load is likely to be 30-50fps per inch--or 60-100 for 2"--faster in a 4" gun than a 2". Short barrel 357 does outdo 38, though not as much as long-barreled 357 outdoes 38. The crucial consideration, though, is that .38 snub velocities are just at--or below--the bottom end of what bullet makers need to make an expanding bullet function reliably. Using a 357 snub--though it is, indeed, a beast to shoot--puts you over the threshold into the ballistic territory where you don't have to question too much whether your bullet is going to work as intended. All you have to focus on is putting it in the right place.