While some people have good luck with sizing the patched bullet, it has never worked for me. For example of my method, for .30-40 I size the core to .303-.304 depending on the rifle. The core is wet patched with .002 thick tracing paper to .311-.312 and loaded. The results are 2 inch groups at 100 yards with bullets driven to jacketed velocities; 215 bullet at 2200 fps in the case of the .30-40.