I had the one in .351 and changed it to 9mm. I ran in the chamber reamer and lightened the slide assembly with holes. I used a P38 mag with a steel block welded on the back to give it enough back end and modified it to take the mag catch. It ate anything you put through it and it was too bad it wasn't auto or had a drum... The original cartridge can be made from .357 mag I think...