Many current gunsmiths will not work on the M99; the complex magazine and odd machining on the breech end of the barrel are apparently too much for some modern gunsmiths (at least that is what three of them told me). Heck, Savage had to simplify the M99's design in the 1970s so that it could be assembled in their factories as the skilled workforce retired away......
Ackley was a great promoter of his products and services, but much of what he published in the handbooks was unpressure-tested data from unsubstantiated sources. The data came from an era when wildcatters competed against each other for bragging rights, and much of their data is: wildly over-pressured, fired in very long barrels, had one-shot case life, required a hammer to open the action, etc. (Regardless of what was published, all cartridges are slaves to the laws of physics - you cannot get something for nothing.) Some of P.O.'s theories have been proven wrong with modern testing equipment - but that doesn't diminish his overall contributions to cartridge development, which were substantial.
It was well documented that early M99s exhibited action stretching with high pressure loads in cartridges like the .250 and .300 Savage. Metallurgical/heat treatment changes were made in the early 1950s, around the time the safety was moved from the lower tang to the upper tang.
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