OK they shot better than any lead load before...no surprise. Now the one thing I noticed was the crimp and it appears to be a roll crmip of sorts and I know from past conversations with the few guys I know who reload, that they say a roll crimp yield a a better pattern. If that is indeed the fact then could the crimp also be part of the Longbeards recipe for success?
Could be but it could have also been done to keep pressure down. I bet it was fun developing the load to be within safe pressures!
As a hand loader, my take is they needed to roll crimp vs fold crimp, because the hull is full, due to the resin. It takes less hull above the top of the shot column to roll crimp vs a fold crimp. They may have had difficulty getting the shot column height low enough to fold properly. There is generally not a clear patterning advantage to rolls vs folds IME. I do both, depending on the height of the finished shot column. That said, the frangible plastic OSC they are using is the least disruptive OSC you can get with regards to patterns. Shells with frangible plastic OSCs can be made to pattern very well, e.g. H13 "Old Whites".