I forget we have outside people reading things here, or just doing a google search for the 'best", and they don't see the entire conversation spread out in a couple of different threads or see the previous comments from an earlier time leading up to the current comments.
they just click in lift the load details and move on with their day.
[I forget everyone can be an 'expert' if they got the latest hand held google machine or a video camera and a U-tube account]
anyway:
the point JW makes about a start in the rifling does make a difference.
I don't think too many give the pressure point from a bullet moving versus jammed into the rifling a second thought.
I know we discussed it in the XCB thread, and concluded even with the very low neck tension I was using the jam start [by letting the bolt closure do the final seating] was raising my start pressures somewhere in the neighborhood of 15-K.
not a bad thing when your dealing with a powder 2-3 steps too slow for the round with 90% case fill and need it to get a complete burn, but this is a completely different thing.
in fact the complete opposite and your actually trying to keep the pressures DOWN.
10-15grs. of a fast powder will still put pressures up high enough to start stressing some of the older rifle types, adding in another variable just keeps that trend going higher.