Badger,

I had good success with MagTec brass in a 12 bore Paradox gun. I purchased 11ga wads and cards and they fit perfectly. The only issue I encountered was that often the cases would extract but wouldn't eject. They expanded upon firing and had to be pulled out of the chambers. It wasn't a pressure issue. The cases just didn't spring back to their sized diameter. It may or may not happen in your gun.