I read and responded (PM) to Tang of my powder bridging experience. I didn't know the cause but an email to Kirby brought me up to date. (He made a side comment that the 721 Rem held up to that test.)
I also read kiwi's post with the purdy pics.
Not to highjack the other thread I have some questions.
I understand the post regarding 'detonation' (I saw it occur once with a 22-243 and 4831 or it may have been an untimely reflected pressure wave. Big boom and rifle in pieces. Impressive! No one hurt)
Bridging may be a bit different than detonation. At least to this simple mind (mine).
My problem in this case seemed to be too much powder trying to follow the bullet down the barrel and "log jamming" at the base of the neck. It would seem that this would/could cause 'detonation' of the bridged
powder as described by Kiwi's pics.
From my use of the RSI pressure lab I would estimate the pressures (didn't use the RSI for these shots
) to be in the very high 70s to lower 80s (k psi) Thus no come aparts or recoil lug problems.
I do shoot about 84 grains of 7828 ssc behind a 150 Nosler with great results. But for heavier bullets I stick with the ball powder.
Additionally I'm confident that all problems would be taken care of with a forward ignition system (flash tube which I've experimented with a bit but the small RUM cases are too small with too high of operating pressures in extreme magnum loads to be of much benefit)