Getting the right fit can require bigger bullets and/or different expander plugs. With the exception of 223, everything I load uses cast. This is mostly handguns with rifles being AR-15s and a 357 Mag lever gun. For the rifles I only use powder coat and none were any problem at all with respect to barrel leading. I can generally use tumble lube for mild to lighter mid range loads. For warmer mid range and full power magnum type stuff, I powder coat. This has worked for a lot of guns and loads. The stouter stuff includes, 327 Fed, 357 Mag, 357 Max, 357 AR Max, 44 Mag, 7 TCU, 30 Herrett, 30-30, 300 BO. Note that I have had leading issues even with powder coat. I struggled with my first attempt at 9mm until I fixed both bullet diameter and made a custom larger expander plug.