.40 magnum rimmed

[SharpsBig50]

Hi folks I'm new to the site. I came across an old post (2013?) about a .40 mag rimmed case that Randy Shelley developed, my question is has anyone worked with this round? Does anyone know what the parent case is? It looks like a .30/30 cut down an resized. Any help is appreciated.

[oldman10mm]

30-30 brass has a wall thickness that is thicker than the wall thickness of handgun brass, pressing a 40cal bullet into it creates a 'bulge'.

https://10mm-firearms.com/general-discussion/10mm-rimmed-case/