As part of my reorganizing all of the brass in my reloading room, I came across about 200 new Winchester 348 cases that I bought 20 years ago to convert into 43 Spanish for my Remington Rolling Block rifle. I had purchased a box of 20 cases at a gun show that were converted 348 cases and thought maybe I could do the same thing. So, what might be the procedure? I tried the base in the rifle and it fits ok, and the length of the case is roughly ok, so the only problem seems to be the diameter of the case just above the rim, tapered down toward the neck of the case. The converted 348 cases measure 0.517" just in front of the rim and the new cases measure 0.542". So, what technique do I need to use to reduce this dimension since I don't believe I can do it forcing it into the Lee reloading dies I have.