Are these 9's? What bullets? My 1st thought is "did you zero the caliper" after each reading? Fresh battery? What COL were you expecting and how many rounds landed within .005 of your target COL? The ones that were outside of your target COL, did you do a "triple check" to get an average COL? Sometimes a high or low spot on the bullet will yank your chain!
BTW....I use a single stage Lee press and Lee dies.
PS...This is my 1,000th post! What did I win?