RE: Beretta customer service sucks
I knew you shot a lot, and yes you are correct that it isn't normal for a gun to pattern that low. You could add an adjustable rib, several of the shooter I know have dun this to correct a gun whose POI is off. It is possible that the barrel isn't concentric, or more likely that the rib itself is just off, I'd call Rich Cole (I believe he's still an authorized service center for Beretta USA), he has been much more responsive than Beretta USA in the past. Actually this isn't as uncommon as we would like to think, but the comment about the shims correcting the POI threw me off and made me think it might be a gunfit issue. Sorry for the assumption. There are even several master class sporting clay shooter that have put an adjustable rib on their gun to correct this problem (if I remember correctly Robbie Purser shoots with one), but I've been out of the loop for the past 10 months.
Gordon