Myself (Ed Hubel) and others on the AR forums have done alot of bigbore wildcattting.
One of our projects is the 12GA From Hell.Like rifle/shotgun a takeoff of the
the old African Paradox guns, only a ten times better brass case.
Rob from the forum came up with the name and original concept.
We built the case from BMG brass and Rob chambered a big falling block,
a Borchardt 50 BMG action, with heavy rifled barrel.
I chambered a Savage 210 bolt-action, with a heavy barrel and a
weighted stock.
Here is a photo of my Savage and the second photo is the 12GA From Hell
next to a standard plastic case.I have one case I fired 36 times and
sectioned it and there was no stretching.Regular plastic
cases will fire in our chambers also, so it's technically
still a shotgun-cartridge, gun.
I also have developed my 700HE belted straight case from BMG brass.
See the last photo on the far right or bottom.Ed.