I don't know of anyone that is offering a "factory" for the 357 Super Mag. I own a 445 Super Mag, with 6", 8", and 10" barrels, and no one offers any kind of "factotry" load for the 445 super mag, which doesn't bother me none becasue I strictly hand load for it anyhow. Starline Brass should offer 357 super mag brass, as they offer 445 super mag brass. But if you really wanted to shoot factoru loads, you can shoot regular .357 mag facotry loads or 357 mag +p loads in it.

As far as Dan Wesson super mags go, there are a quality piece. And speaking only of the 445 super mag, it is an awesome hand cannon for a double action six shooter.