9mm Luger Dies for .38 Super
Well, as the previous post says, the Luger case is tapered, the Super isn't.
But.....
I load 9mm Largo (measures 9x23) in Luger dies - which the manufacturer agreed should work fine, not unlike loading .357 with .38 special dies. Not the best arrangement - they'd rather you do it the other way around, but okay.
I have a bunch of .38 Super brass that I tried just for the experiment, to load in my 9mm Luger dies while I was set up for the 9x23 dimensions of the Largo.
The Super has a little bit of a rim, and Spanish pistols at one time were often made for Super as well as Largo and were said to be able to chamber both.
Important safety note - I'm talking dimensions here. I am NOT saying you should see what will chamber where just to shoot extra ammo in the wrong caliber. Some of the old Largo pistols are DANGEROUS if you try to stuff .38 Super ammo in them.
DON'T DO IT.
Anyway, I loaded some .38 Super casings using the 9mm Largo settings and a reduced charge. What I found was the Spanish pistol does in fact kinda sorta work with Super cases loaded to .38 Auto pressures after being run through the dies. Sometimes. The extraction and cycling went fine on the ones that chambered, but not all of them chambered.
SO - it will work - but poorly. You really should be using .38 Super dies to reload .38 Super. It's worth a few bucks to get the right dies.
I don't recommend fooling around with this sort of experiment unless you really know what you're doing.