The Problem with the Eddystone is that the forging operators turned the temp up on the ovens so they could skip several steps in the forging process and just stamp them out quicker.
With the Billets being held at a higher temperature for long periods of time, the steel underwent a process that turned it brittle. I don't know what the serial number ranges are, but that's why they were able to turn out more rifles than the Remington plant in the same amount of time.
The actions can let go if chambered in higher pressure cartridges. I'm trying to remember the source for this info, but I've got a serious case of CRS at the moment.
Maybe this will jog someone elses memory that knows more detail on the subject.