Thinking that maybe that my load is not hot enough for Brinell 18 hard bullets, I plan to up the powder charge within safe limits to see if that helps.
I would suspect the same, but i'm not sure boosting the bullseye will help. I never shot cast 9mm over Bullseye, but with jacketed bullets the accuracy was horrible. On the same day I tested Bullseye is also tested Blue Dot, and it immediately became my pet load. I have since become a cats fan, and my 125gr cast over 8.0 gr of Blue Dot shoots both clean, and super accurate. I got good results from unique as well, but not as good as Blue Dot. I've never found a Bullseye load for 9mm I was happy with. I think its a little fast for an auto bigger than .32acp.