There was pre-ignition, there was two flame fronts colliding, there was knock, anti knock? All having to do with Ethel (
http://www.thefreedictionary.com/tetraethyllead) in the gas tank, then there was timing and the ability of the ethyl in the gas tank to prevent knock. Then came auto mechanics, auto mechanics applied the theory/principles of combustion in the chamber to combustion? in the chamber, and, to them it made sense (to them).
(Then someone wrote and recorded a song about having Ethel in his gas tank and no girl in his heart)
There was a phenomena that involved chance, meaning it will not happen every time but, there is a slight/remote chance bad habits will result in the next round fired will render your fire arm scrap, the auto mechanics did not buy into a foreigner getting into their business/theories/principals. The foreign company went on about their business, they claimed time was a factor.
Powder ignition can be position sensitive, I am not the fan of spreading my powder thinly across the bottom of the case when laid on its side (as in from the bottom of the case to the base of the bullet). When the trigger is pulled there are two speeds to consider, the ignition of the primer and the burn speed of the powder, I know, ‘it’ is fast, but, I have been at the range when a shooter/reloader was in mortal combat with his pistol, he could not pull the trigger, he could not open the cylinder, he could not get the cylinder to rotate. In short his Model 66 was locked up, he had a bullet stuck between the cylinder and barrel. One of his newly reloaded rounds had no powder, the primer launched the bullet.
then there is the two speeds to consider, the primer and the powder burn speed, the primer is the fastest , the powder comes in second, then there is the powder position, if the primer can launch the bullet into the forcing cone the bullet can have a running start but because time is a factor the bullet can stop in the forcing cone at the rifling, then comes the powder burn with an increase in pressure, everything is working, not as planned but working, when, suddenly and without warning the expanding gas caused by the burning powder has no place to go, the bullet is jammed, without time to get it moving again, the rise is pressure exceeds the ability of the fire arm to handle the pressure, as a results, the fire arm is rendered scrap.
Excuses: “I ‘musta’ had a double charged case....etc.. or “It handled like a doll buggy right up to ‘pulling the trigger’, like the Deacons Masterpiece there it lay all in a heap” or “All I have ever feed it is reduced loads, nothing but a steady diet of reduced loads”. Back to the phenomena, “It does not happen ever time, it can happen”, the foreign company moved on doing what they do and reloaders still return from the range with firearms rendered scarp without a clue. Reloaders apply a strange standard to the phenomena, if reduced loads cause the problem it should do it every time as in a repeatable results.
Then there is the DUH factor in reloading. “WHAT HAPPENED?” “I DON”T KNOW, I MUSTA HAD A DOUBLE POWDER CHARGE!!” Go through response that involving case weight and measuring, the most irresponsible answer has to do with accuracy. The last chance a reloader has to prevent an accident that could prevent rendering their firearm scrap is before firing, back to weighing components, if a reloader does not know the cases weight before loading there is no way to determine if a case has too much or not enough powder.
I loaded 250 rounds of 30/06 on my Dillon 550B, after I finished I weighed ever round, there was 18 grains difference between the heaviest and lightest, not a DUH moment, there was that much difference between case weights.
Back to the range with the shooter with the Model 66 S&W, we drove his bullet back into the cylinder, in his mind everything was good to go, so he started to chamber 6 more reloads, and we had issues with that, he did not know if one of his cases got no powder and the next case got twice the recommended daily dosage, he did not weigh his cases before and again after, we could not convince him a scale, bean or digital, could distinguish the difference in weight between a round with powder and a round without powder, we offered him all the ammo he could fire, we offered to help him with his reloading, we offered to give or loan him equipment to go with his brand new Dillon 550 B. He packed up all his equipment and left.
Then there is the BIG TRAIN WRECK, an event staged between two trains, bleachers were set-up, spectators were knocked off the bleachers, backwards, the train wreck had nothing to do with reloading, but there is another phenomena, pack a case with powder then pack the case with a filler, pull the trigger, between the expanding gas and the filler is a collision, it is possible to ring the inside of the case when the filler expands and or is compressed, I am not a fan of reduced loads, when I form cases I form first then fire, when I eject a fired case it is ejected as a once fired case, others fire form.
F, Guffey