I was wondering if steel cases can be loaded to the same pressure as brass cases. Are the cartridges that commonly feature steel cases like the Russian 5.45x39, 7.62x39 and 7.62x54R loaded to a lower pressure than their C.I.P. MAPs (380 MPa, 355 MPa, 390 MPa --gt; 51,488 psi to 56,564 psi)? There must be a reason why most NATO armies use brass cases...
Steel cases are harder to manufacture, but cheaper in material. Loaded? Yes. Those cases are a very mild steel, and will 'flow' well enough to seal at the pressures involved. The question might come up with low pressure loads though. RE-loaded?? - I wouldn't try it, even if they weren't berdan primed.
The ammo loaded in steel casing has a tendency to be loaded at lower pressures, for some reason. Most if not all of the steel case is of foreign manufacture. No reason steel can't be loaded to same pressures to that of brass, would probably seal better. Most of the calibers you describe in steel cases go in weapons with loose tolerances, like the AK. Lot of times, the steel won't seal in the chamber, creating blow by, putting crud in the chamber. This condition makes it hard to feed, chamber, and extract in a tight dimension chamber that is present in NATO weapons. AK's, due to more generous tolerances, won't be sensitive to this.. Weapons from NATO are of more tightly toleranced chambers like the AR, HK, Barret, etc. where brass is more reliable in sealing, and minimizes the blow by and keeps things clean, or at least more clean than a steel case that may not seal.
