Of course the obvious answer is to go with a firearm that is already a 10mm. I have seen a lot of old war rifles (Arisakas and Enfields that were rechambered to either 308 or 30-06 seem to be the most common, there are others) I've just been rolling it over in my head for a few days especially after the thread on ammunition diversity so I am finally going to just throw it out there. How hard would it be really to convert a Beretta CX4 storm (carbine) w/complimentary PX4 (pistol) from 40 S&W to 10mm? First I think the barrel would be the easy part and modifying the magazines the hard part but if those were do-able is there anything I am missing... 0h, perhaps upgrading recoil springs. I am interested in doing this, perhaps even try it myself. What are the thoughts or recomendations of any gunsmiths out there? Has someone already done this with the above mentioned guns (or any other guns)?