4ga buckshot , zombie gun !
You understand my thinking on the RV85
perfectly. And why I've submitted an ATF "Form 1" and $200 o get it made a Destructive Device.
If anyone's aware of the old 4-bore Rodda safari rifles, I
think at minimum, the RV85 can handle anything they did, considering the RV85 is CZ Brno forged 1980's steel, and the Rodda was late 1800's spiral wound Damascus.
The barrel/chamber thicknesses seem to be roughly comparable.
The RV85 has no rifling to engrave or swage into, so bore obturation should be lower, hence lower pressure.
The round would be fired from a re-usable stainless steel casing, which would provide more support and pressure containment than brass. (OTOH, it may swell less, and provide less grip than brass, and hence more chamber face thrust...)
My one problem is how to
prove it, without unacceptable risk to my RV85, or my own extremities, and no fancy tools like pizeo stress sensors etc.