Less than 100 of the 1903 Springfield and Rock Island Rifles were destroyed because of the receiver failing, and all of them had exceptional circumstances, that caused or at the very least contributed to the destruction.
About 25 had the "Proof Test" rounds fired (many times), and through excessive pressure the receivers were "work hardened" by stressing them above the "Yield Point". They failed!
At least 35 failed because soldiers had been dipping the bullets in "Oil" before loading them. This increased the chamber pressures to the point that the receivers failed! It seems that this was a carryover from .30-40 Krag days when some soldiers found that they could cut down on the "Copper Fouling" near the muzzle (copper bumps would develop near the muzzle, over a short time, and this affected the accuracy) by dipping the bullets in the oil. It was believed by the soldiers that this was a necessary precaution, so they blew the receivers up through ignorance. They failed!
Others maybe another 15 to 20 failed when overloaded hand loads were deliberately fired in them, some over a fairly long period of time. They failed!
There is no way of knowing if some of the rifles blew up in combat (I am reasonably sure that there would have been a report that mentioned it, if even a few had failed).
As to the heat treat being improper, there is always that risk, even with the proper tools and measuring devices. The blame for the heat treat problems should not be resting entirely on the shoulders of the heat treaters. Most of the "Old Timers" were very capable of doing excellent visual checking of the heat treat as it progressed, and had done so all of their working years. YES, bad lighting conditions very definitely would have affected the precision of the Heat Treatment, and the same thing has recurred using the "Latest and Greatest" equipment. If you don't know what to look for, you are going to make major mistakes. I worked for quite a few years as a Blacksmith, and believe me you have to learn tricks of the trade in order to be on time.
I had read that when the production was ramped up for WWI; there were many people hired to push production (normal procedure). New blacksmiths were hired, and many had no training or very little, this combined with "New Production Engineers", was a shortcut to problems. Cutting corners is a quick solution, and very definitely can cause very serious problems.
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