I myself do not push the max load; I recently did change powder because powder I was using has sensitivity to high heat and humidity, I have found that most my loads are with in the 2/3 marks and seem to be most accurate. accuracy was more important than speed.
pasky2112: I am Wonder why you felt need to obtain 1200 fps what was the driving force on this,
Thoughts for road since I am fairly new,Recommendations from older reloaders ,
Get good scale and check it often,
Check power loads often,
Workloads up slowly
Check data source from multiple books, powder sites.
I still wonder the amount of powder best I can see was too much , listen to some of the older more experience members : two that come to my mind right off are Fred , Colorado4Wheel, I can tell you sometime they get sarcastic but there most time dead on , make this a learning lesson , I am glad you are ok , what exactly happen who really knows other than my thoughts are still too much powder charge .