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Er...actually...and don't hold me to this....

But I don't know any IPSC reloaders who would double charge a case. In fact, about 99% of any double charged pistol cartrige will result in catastrophic failure FIRST time, every time. Also, I do believe that a double charge is practically guaranteed to damage the weapon! It takes far less to just blow a case head. :-)

HOWEVER....there was a great mystery back around 1990 or so whereby a lot of IPSC shooters were blowing up good guns (mostly Colt Series 70s) and for a time, nobody could figure out why. From what I read, a great majority of the blow-ups were light loads. Somebody (and please forgive me for my lack of references here because it's been a LONG time) finally concluded that it was a phenomenon called "flash-over". I remember reading that they were able to reproduce it as well, at least to some degree.

From what I understand, flash-over is where a very light load spreads itself out along the inner case wall when the weapon is lowered to a horizontal position to fire. It was determined that this presented a LARGE area by which to produce a flame front via primer ignition. Then, instead of having a flame front consisting of the inner diameter of the .45ACP casing, there was one that could extend the length of the inside of the casing! In short, TOO much ignited TOO fast, building TOO much pressure, and *ka-boom*. We know the rest of the story. :-)

But anyway...that's what I remember about IPSC shooters having a bad rap for blowing up .45ACPs. :-)

I beleive you are correct, the same thing occured in the rifle target shooting fraternity and the issue was resolved by using an innert filler (cotton balls) to hold the powder in place. Powders are designed to burn at a specific rate and that rate is controlled by grain size, shape, and coating. Changing the surface area amount exposed to burning can cause the charge to burn faster causing a spike in pressure.

They were not double charging on purpose. They were loading fast powder that didn't fill the case, such as WW231 or Bullseye, and not noticing the double charge. The theory of detonation, or flash over as you call it, has never been proven.

And a double charge will not destroy a pistol if the case fails first. It actually acts as a safety valve and releases pressure down the mag well, usually blowing the mag out and cracking the grips on a 1911. This is one reason the pachymer grips were so popular, they had steel inserts in them.

I can't find any reference to the federal recall of 40S&W ammo, but will continue to look.