All you have to do is get your self some 5mm Craig dies and your are in business. The 5mm Craig is the same as diamentions as the 5mm Rem. rim fire. Cases are easy to make from 22 Hornet. I looked for a 5mm Rimfire rifle for several year to convert it to center fire for year, untill they brought out the South American ammo just to convert to center fire, but you have the best of both world. You can fire eather rim fire or center fire by just flipping a lever.
