I didn't know there was such a thing as a scandium frame J-frame until I fingered a M340 at a gun show. I didn't need to do much reading on the Internet to realize that a .357 Magnum in this light a revolver was way too much of a good thing. I didn't even like that cartridge out of my 4" M66. I had a 22 ounce early stainless M60 .38 Special only, but thought that was even heavy for a pocket piece. S&W did make a scandium frame .38 Special only version for four years about 20 years back called the M337PD and I bought a nice one out of Georgia a few years back. At 12 ounces loaded with Special +P it is all that I want to hang on to, but it sure does fit nicely in a pocket. I would put longer rubber grips on it if I shot it more often, but at the cost of better concealability.
