You could probably do it quickly and cheaply with a hacksaw, but I don't recommend it. For a hefty charge, a good gunsmith could cut it down, re-crown the barrel and fit a front site, or change the barrel entirely. But if the barrel is not currently damaged and in NEED of replacement, it's not recommended. A 7'' barrel on an S&W is somewhat unusual, and altering it would ruin any potential collector value.i have a s&w .357 mag with a 7" barrel. im new with revolvers, and want to know how hard it would be to convert it to a 3", or 4" barrel for my ccw.
If you really want a shorter barrel, buy another gun or trade that one in for something else. Of course you could always get a Dan Wesson which has interchangeable barrels and go anywhere from a 2" to 15" in a few minutes.