I think Denis and others nailed it on the Largo/BB. I've little doubt that some Largo or BB factory ammo may have, equaled .38 Super ballistics, but my 14th. Ed. Speer manual shows loads at a lower pressure, due to some of the guns the Largo/BB might be fired in, that don't quite equal the commonly available 9x19MM.
BTW Ascot, I have used RCBS, and later Dillon, carbide dies for many years and have never had to lube 9MM cases. As to an untapered, rimless alternative to 9MM, FWIW I have been using the Starline Super Comp cases for loading 38 Super. The SC cases are not tapered like the 9X19 and are rimless, or nearly so. I have found the SC cases to feed very smoothly, and be less likely to nosedive from the magazine than the semi-rimmed 38S cases...ymmv