it is looking as if our near-liquid lead alloy bullets are being distorted in the first inch or so upon ignition. it is not as clear that running out of lube or stripping/gas cutting, or melting due to barrel friction after the first 6 inches is unavoidably present.
partial success in out quest to match jb accuracy is probably due to schemes to align and support as much of the bullet as we can before firing.
and probably by using as hard an alloy as we can find .. maybe the end goal would be a strong metal jacket ( g ) .
also it seems that keeping g forces lower ( thru slower burning rate powders and very long barrels ) results in less bullet deformation for the same muzzle velocity. honorable mention goes to having a high quality barrel .
the above is an attempt to pause, inspect the past 600 years of shooting lead, and see where we go from here. that we attain an easy 2 to 3 moa by following 4 or 8 rules i consider amazing !! harry pope knew these rules 100 years ago but only with the internet have the rules been so available to so many interested in improvements.
as has been dutifully noted , and with precious truth indeed ... that wonderful schemes and midnight inspirations do not make great targets without some investment of time, sweat, ...and yes often money ... still it is useful to have a few hundred possible fantasy improvement scenarios in hand for our subconscious to sort out on our road to beating the curse of cast bullets always being that other child.
so what do we try next ? accuracy with velocity is near ;;; i can sense it !!
ken
Point being, while there may be “little blips” on Larry' traces, we don't know what they are. There seems to be an awful lot of jumping-to-conclusions going on. I've done a fair amount of pressure tracing with high velocity cast, and don't recall seeing any “little blips” that might correspond to engraving. Bear in mind that the raw signal from a strain gage is very noisy, and is usually filtered by both hardware and software before it shows up on your computer screen. It can be particularly tricky for a pressure trace to capture the true point of ignition, because there is a lot of noise that can be mistaken for ignition. I.e., I often get false “ignition” if I jiggle the cable or if I close the action hard. That said, I do appreciate people sharing their shooting data, blips or no blips. 
ude: While I don't plan to try breach seating myself, the breach seated data that has been presented is very useful to prove a point -- that, as others have said, high velocity cast bullets fail mainly due to something going wrong in the throat. We can debate what that something might be, but I agree that the passage through the throat is the weak link. As I recently posted on another thread, the weakness of Dr. Mann's otherwise great book is that he paid no attention to the throat. He started out claiming that best accuracy was obtained by seating bore-diameter bullets (through a false muzzle, if I remember correctly) in his BPCR calibers. Towards the end of the book he switched to smokeless calibers -- which probably had a decent throat though he didn't say -- and began getting satisfactory accuracy with conventionally loaded cartridges. The book on the ideal cast bullet throat has yet to be written, as far as I know. I appreciate you guys adding your data to the knowledge pool. 
