Nice! That is really interesting and if a person really thinks about each and every action and reaction, logical. The case neck retention, coupled with seating depth and contact with the lands, are the forces it takes for the pressure from powder ignition to release the bullet down the pipe. With the ammount and shape of the powder you will always have a variance with how much combusts before the excess is thrown out of barrel unignited.
I might haveissed it, but how crucial was barrel temperature? Were five shots few enough that they didn't get that much of a temperature differential from format to last shot?
Thanks for the post!