Hi Folks, If you have been reading online gun forums for long, you have undoubtedly seen mention of a phenomenon that could be called "light load detonation". Now, based on a great deal of reading of the reports of this phenomenon, the reports of guns destroyed by unknown causes, and guns destroyed by double charges, I am inclined to believe that double charges are almost always to blame. I can think of one other possible mechanism for failure when shooting hot handloads. There is a condition familiar to engineers called "constructive interference of dynamic stresses". Constructive interference in an elastic medium can cause stress to be doubled. It occurs when stress waves reflect off of each end of a structure, for example a cylinder, and return to meet at some point near the center, resulting in a peak stress nearly double (sometimes more) what is calculated for static systems. In all real mechanical systems there are dynamic stresses that exceed calculated static stresses. This is the reason for the seemingly arbitrary engineering safety factor of "2", which you see now is not so arbitrary. The usual methods of stress measurement in guns is a real dynamical measurement, and therefore all contributions to the measured stress are accounted for, the safety factor is intended to account for material defects, not for overloads or deep seating. That is why gun design engineers warn against EVER exceeding book load values. That said, I do it myself. I hope that if you are doing it you are taking precautions to avoid injury in the event of blown cylinders or, WORSE, a blown case in a pistol setting off a mag full of bullets in your fist. You are at the mercy of your weakest case when your chamber is not fully supporting. The makers of large guns and cannons perform a pre-stressing treatment called "autofrettage". They seal up the gun, muzzle and breech, and then fill it with water or oil under very great pressure to just under it's yield point. The result is that a residual compressive stress is induced that can as much as double the ultimate strength (hoop stress limit) of the gun, and can increase it's service life considerably. A similar result is NOT achieved by cryo-treatment, as is sometimes claimed. As with everything I write, I invite questions or disagreement. My intention is not to "take on all comers", but to educate.