"In a 1927 Western Cartridge Co. flyer "Super-X The Long Range Load" by Capt. Chas. Askins the 12g duck load is described as 38 1/2 grains or 3 1/2 dram (powder not specified but likely DuPont Oval) with a breech pressure of 3 3/4 tons or 11,480 psi."
Miller: I'm sorry for the confusion. Askins said only 3 3/4 tons; I calculated the 11,480 psi.
I still don't know how to interpret the 28 grains of Ballistite running 12,600 psi (by LUP). Add 1000 - 1500 for piezo numbers and we're close to proof loads. How could these ol' boys still have all their fingers!?!
tw:
"Rather, it is a stressor that is independent of velocity whose effect is also cumulative and it affects weaker/older mild steels more so in terms of cyclic life than more modern alloyed steels w/higher pressure tolerance limits."
In the ONE formal failure analysis that I financed, there was no evidence of low cycle fatigue.
From the report by Adam Haskins at METL
http://metl.com/services/ "The fracture surface exhibited a mixture of ductile overload (plastic deformation with both tensile overload and shear) and transgranular cleavage, indicating a ductal failure mode with rapid failure. The cleavage failure appeared to form preferentially in the iron component. No evidence of fatigue failure was observed; there were no striations on the fracture surface."
I've submitted a 2 part article to DGJ, which also includes the analysis performed by 'Zircon' on the Sherman Bell fluid steel and Damascus blow ups. No decision as yet if it will be published.
