I believe it was designed for the Widley pistol and was a 9X29 straight wall case.
It was a caliber designed for a firearm that had a short life and no other company picked it up.
Kind of like the .45 Win Mag.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
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Former President of the ECPT (Eifel Combat Pistol Team)