Super-X Slugs

I just got a gift box from a neighbor of bunch of “OLD” shotgun shells found in their Grandfathers basement. Nothing of much interest. Just the usual assortment of 1950’s era stuff. Plus, I don’t collect shot shells, but I never turn down a gift of cartridges. You never know when the next gift might come from a ex-employee of the XYZ Ammo Co. Experimental Bureau.

Anyway, among the stuff was the below pictured box of Western Super-X Slugs. When I opened it I found 5 factory loaded slugs loaded in cases with “SHORT SHOT STRING SUPER-X LONG RANGE LOAD”. My question is, was it common to use any hulls available at the factory to load slugs?

I know the scan is terrible, but it shows what I have a question about.