Dr Lyons' analysis is a hot wet mess. He applies his risk assessment against the whole population of single heat treats, and they were not all in service at the same time. Some where on my desk I found Infantry number in the 1920's. Off the top of my head, Congress authorized 40,000 infantry, but actual troop levels might have been 30 k something. And then, I would say, few of them are pulling triggers. Go on an infantry base and see how many Soldiers have rifles, and how many are shooting at any time. You probably won't see one Soldier with a rifle, and the only time they shoot, is as a unit. I recall seeing numbers to the effect of 20 rounds per year per Infantryman. Maybe less in the 1920's. Post WW1 appears to be worse than Post Vietnam. At least the Soviet Union was around to maintain some level of funding. Money was tight. One bud, his unit spend the entire month's fuel budget driving the unit to the motor pool, to be fueled!. Post WW1 appears to be worse. A guess is maybe 10,000 rifles are in use at any time, world wide.
Then, and this is an important point, Dr Lyons' assessment ignores the intrinsic characteristics of low number receivers. He assumes there is nothing about SHT receivers, the factory they were made in, that has any relevance to why they break. Reminds me of medicine before germ theory, a sort of "if she dies she dies and no one knows why". Why SHT receivers break is all about heating metal up without temperature gauges, is all about unknown steel compositions, it is all about a factory whose process controls are so sloppy that non heat treated receivers make it out the door, and into the hands of troops. But to Dr Lyons, these receivers just fail, nothing particularly note worthy when one fails, nothing particularly special about this group, just a random event unrelated any characteristic that SHT receivers have, compared to DHT or the nickle steel receivers, or the factory that made them.
And Dr Lyons is a Medical Doctor. I saw numbers that through medical mistakes, Doctors kill about 250,000 patients a year. Dr Lyons' analysis is one clue why that is happening.
Sedgley bought scrap M1903 SHT receivers from the Government. I read that somewhere. I also read in two places, Sedgley did not heat treat these SHT receivers, he annealed them. Which made them dead soft.
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By the 1940's, a Dope Bag article describes these rifles, but not explicitly naming Sedgley ("one of those Philadelphia outfits") as blowing up all over the place. This was well before Product Liability. You bought a dangerous product from a manufacturer, one the manufacturer knew, or should have known, and you got hurt, too bad.