Yes, detonation is a theory, but it is a credible one. It is based on the same principle that breaking up large powder granules changes the burning characteristics by creating more surface area. It is also an old theory because nobody has proven, or disproven, it without doubt.
I do have my own theory about the rise in kabooms, and I'm not saying that detonation isn't possible, just that it could be more than one thing. The rising cost of ammunition and the increasing popularity of shooting sports among people that would have never fired a shot otherwise has driven people to reload that really don't have their heart, or brain, in it. Even long time, epert reloaders can divert their attention long enough to cause a problem.?
The reason why I posted that previous comparison that somebody did w/.45Colt was to show how small loads with even a slower powder like Unique had some pretty significant velocity spreads and velocity standard deviations when the powder was situated either right on top of the flash-hole or when it was situated at the back of the projectile/far away from the ignition source. If you look at what that guy discovered, he was able to show that based upon powder position in the case, he experienced @15% to almost 20% reduction in velocity in some cases (and higher extreme vel. spreads) with the same powder charge/primer combination.
For this particular .500 Kaboom, I have a feeling that the same issue that was shown with the Unique in the .45Colt cartridge could have resulted in a .500 projo getting stuck in the bore, the shooter was not aware of this dangerous situation, and the next round fired could have caused the actual Kaboom to happen.
BUT, on the detonation issue, I think Jellybean DOES make some very valid points when he talks about powder grain surface area variations due to individual propellant grain fracturing/crushing to significantly increase the surface area of a load and thus dramatically change burn characteristics. For small-grain ball or even flake type powders, one would think this would not be too much of an issue "normally". But with my own experience as a match .50BMG reloader/shooter, I can tell you that this is a HUGE issue for larger grain propellants.
Whether any of you know it or not, the faster burning smokeless powders (the tests I read about were done with Bullseye in particular) WILL detonate with surprising brisance in the right situations. The usual determinant factor in getting them to actually detonate is having enough propellant exposed to the initiator (tests were done with a #8 cap) so that the detonation wave will propogate completely throughout the propellant.
One would think that with some of the extremely small loads which have been reported to have "detonated" instead of "burned" that this "perfect detonation wave" could not be possible, but I have always wondered if a "perfect" situation could ever accidentally arise where an individual load was comprised of a large portion of "crushed" individual powder kernals (so individual broken-kernals have even less space between them than normal; which makes it easier for the det.-wave to transfer between them), and when this reduced-load gets sealed inside a relatively significantly sized and completely enclosed space like a reduced-load cartridge case is, it could allow for a perfect "harmonic" of sorts to be caused when the primer fires and thus create a more efficient "detonation wave" in the propellant rather than the slower/preferred "burn/ignition"...?
It's all theory when it comes to all of this coming together inside a cartridge case of course, but the faster smokeless propellants DO detonate quite nicely when the situation is right... The report I read said that Bullseye was just about equivalent to the detonation speed of TNT, which is "military grade" explosives!
