You don't need to plate cast bullets to shoot them at jacketed bullet velocities, unless you're shooting them in something crazy big. We've had really good results in the 2600+ fps range. Larger diameter cast bullets seem to handle higher velocities better than the little ones. We've run 375 H&H up into the 2700 fps range with gaschecked cast, but I will admit that I've never even considered doing it with a 223 or 6mm. When you shoot cast bullets really fast, you need to really have all the kinks eliminated from both the gun, and the bullet/load combination. With most handguns, jacketed velocities are easily bested with cast.