25.4x148B for Solothurn S19-100

In a report on the history of Solothurn Waffenfabrik I have found this drawing of a 25.4x148B cartridge which was described as having been for the S19-100 gun.
As the caliber is exactly 1" I wonder if the caliber was a requirement of a potential customer maybe. Here in particular Argentina as they are known to have adopted a 1" Vickers AA gun (for their navy). Maybe the S19-100 was a competitor?

Is there more info on the gun or the ammunition? Any photos available?

There are no photos of the gun or ammunition that I’m aware of, but there is some more information (given in the July ECRA Bulletin, item 639-10, from Robert Gerber). The HE shell shown weighed 280g, there was also an AP which weighed 300 g, no muzzle velocities known.

The gun was recoil-operated and fed by a side-mounted 16-round box magazine at a cyclic rate of 250 rpm. As mentioned in Musgrave (German Machineguns) three mountings were proposed: S20-100 (light infantry mount); S20-200 (portable tripod mount) and S20-300 (twin AA mount. None of these was built.

Tony, thanks. After having seen several Solothurn product brochures from this time period I hoped somebody would have one available on the S19-100 somewhere.

I wonder if it is some upscaled version of the 20mm gun.

Seems this gun is a small mystery.