There are some great suggestions here...but things like lube, primers, annealing, bullet weight/size, powder charge, etc is what you change to "tweak" a load.
If you are tumbleing bullets...they are too hard.
Even if they are too small, they will bump-up with black powder..."if" they are soft enough.
Maker of Horse Tack and Cowboy Gear.
Mister, why do you carry a 45? "Cause Sam Colt don't make a 46."