maybe i didnt explain it very well
it went something like this....... you need the ball to enter the rifling as slow as possible, therefore by loading it right at the front, it will do just that as it's only just got moving before it gets there. If seated deep into the cylinder, it will be moving faster and not engage the rifling nice and evenly but tend to strip and cause innacurate flight
that was my understanding, maybe i got it all wrong, don't know, but this guy knew his stuff, he also knew which chambers gave the worst performance in his collection and fires a 5 5 3 sequence