If you look at boat tail rifle bullets, they don't seal the bore at the back either. I don't think you will experience any problems with it. I have a friend who machined some rifle bullets from copper bar stock and just about blew his rifle up. The solid copper doesn't upset to match the rifling like a jacketed lead core bullet does. He went back to the drawing board and machined driving bands, relieving the remainder of the bullet to land size and they worked fine. You might start your loads at the bottom end of the chart with the bullets made from 40sw cases and see what the pressure signs are.. Just a thought.. Blitzfike
