What's the best (and inexpensive) way to do it?
"Best" way is to have Lee handle the problem...and the will because if it produces a bullet that is a different diameter from what is stamped on the die, it is likely faulty (or your alloy is springing back). Also, they will not hone the die out of round, where you may do so by using home methods. The "inexpensive" way is to follow the instructions given in posts here, and hope for the best...learning by doing results in lots of things in the trash bin. Take your choice.
Sometimes you get what you pay for, sometimes you only pay more for what you get.
Three shots are not a "group"...they are a "few".
If the Bible is the literal, infallible, unerring word of God...where are all those witches I am supposed to kill? (Exodus 22:18)