Considering that changing a 9MM Largo to shoot 38 ACP or (With stupidity) 38 Super amounts only to opening that rim area at the back of the chamber (And/or breechface if spotfaced for the rim) it's easy to see that 38 Super dies do nicely, and I've loaded quite a few with 38 Super dies. The rim of the 9MM Largo is 14 thousandths smaller which is the main difference dimensionally, but I am pretty sure I use the 38 S shell holder too. But look at the reloading books at the cartridge dimensions for both to make your own mind up.
9mm Largo, rim dia. .392, case dia forward of groove .390, case dia at mouth .379, case lth .910
38 Super, " " .406, " " " " " ..384, " " " " .384, " " .900
9mm Largo, rim dia. .392, case dia forward of groove .390, case dia at mouth .379, case lth .910
38 Super, " " .406, " " " " " ..384, " " " " .384, " " .900
