Thank you for the title/author... I'll add it to my library.
Re "do we want a stronger or more perfect edge", I'm suggesting the answer is YES (both, but substitute "sufficiently strong" for "stronger"). If there is correlation between consistent accuracy at increasing velocities and bullet hardness (or checking), and it is for the reason I am proposing, then you want both a more perfect edge and sufficient hardness to maintain it at bullet/bore departure.
So yes, we want the most perfect edge we can get. But if we start with a perfect edge and too soft a base edge metal at sufficiently high bullet base pressure at crown departure, then forces from angular inertia and base pressure may tend to bugger up the base edge and spoil a symmetric departure of the bullet... I suspect the largest factor in most situations would be due to asymmetric gas venting.
This is just a theory I'm proposing here. ANY good theory should be falsifiable by a reasonable experiment. That's why I just flat out loved Molly's thread, here
http://castboolits.gunloads.com/showthread.php?t=116741 (
)
In like spirit, I suggested a couple of experiments in the OP. Here are some more that could support or discount what I've proposed.
I think you can demonstrate when and to what extent gas jetting at departure can destroy accuracy by baselining an accurate barrel/lead bullet combo for accuracy and then change only the crown at the bore. This would be done by introducing a single small nick at the bore-crown edge that will allow early/asymmetric gas venting during bullet/crown departure.
another experiment:
I'll bet if you create (on an otherwise well performing plain base bullet) a base edge imperfection that allows gas jetting at the crown prior to/at departure (but doesn't affect obturaton of the bore during internal bore travel), you will see significant degradation of accuracy. Also, that this degradation in accuracy will be greater than that seen from creating an imperfection at say the leading edge of the rearmost lube groove that would comparably imbalance the bullet (so if this held true, it would tend to suggest the effect isn't due as much to balance as to departure/venting).
another experiment:
Base edge imperfections should have less impact to inaccuracy when bullet base pressure is lower at bullet/crown departure. What if you fired the same bullet with a created base edge imperfection from the same barrel first unported and heavily ported (and fully deburred)? (oh! for the shop resources and know-how of a P.O. Ackley
).