Several things you can do to achieve max velocities. #1 - make darn sure they fit your rifle's barrel. Push a soft slug down the bore for measurements as well as to get a feel for any loose or tight spots. #2 - make sure your cases are within .010" of your chamber length. This is really hard to do with most 30-30 rifles. The current factory cases are usually .100" or so short. #3 - make sure the bullets are hard enough. 15BHN isn't gonna cut it for high speed with plainbase bullets. You can try heat treating some and see if they harden up. If they have antimony and a little arsenic in them they'll harden. #4 - use good lube. Tom Gray's or LBT blue. #5 - poly wads or soft wax gaschecks will be beneficial. Of course if you just want to shoot cast bullets at full throttle out of a 30-30, just use gaschecked ones, water dropped, with any old decent lube and you'll max out pressure before you get bullet failure. But plainbase is so much more interesting of a challenge!