Greetings @
Blair,
A couple of things to consider. I suggest you weigh your perfecta cases. The ADI data was developed by Hodgdon using, as far as I can tell, Winchester brass. This weighs about 167 grains without primer. Some continental cases such as GFL weigh 187 grains which is similar to some of the military cases. These heavier cases have less capacity and drive pressure up. The long boat tail projectile you are using will stick well down into the case further reducing capacity. The other factor is the crimped primer pockets which I assume have been reamed. If this has been over done the primer pocket may be loose which I think is the more likely cause. The old suggestion was that max loads should be cut by 2 grains for military cases which would suggest that your loads could be about 2 grains over book max assuming your cases are heavy. It is a pity you did not chronograph your loads as this would have helped with diagnosis. Let us know how you get on.
Regards Grandpamac.
PS. I just went out to the shed to have a look at my GFL cases and they have the unusual segmental crimp that your Perfecta cases do. I believe that Fiocchi make both head stamps although others may be able to comment on this. Weighing one will tell all. I made up some test loads with GFL and Hornady cases which weigh 187 grains and 166 respectively to test velocity but have not chronographed them yet. Will try to do that over the next week.
GPM.