It takes a surprising amount of lead to get 30 grains and ends up leaving you with a pretty short taper on your shaft, which affects strength and alignment. I've drilled the shaft and inserted 1/8" lead wire; it weighs 35 grains per inch. That works quite well, but is a PITA. I used a jig in a drill press and found 2 inches to be the max practical limit for me. There is a drill guide available, but it is less accurate than the press.
Let me know if you want some lead wire to play with, I have more than I'll ever use.