Quote:
Originally Posted by john70t
I think it has to do with case lip expansion, and then sealing and fouling of moving internals. Powder chemistry may be involved.
Plus wear on the slides and extraction mechanisms.
IDK. Still learning.
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The cartridge case is meant to act as a "gasket" of sorts. We use brass because it is soft enough to expand at the case mouth under the pressure generated when the powder burns. If it fails to fully seal, we get that burnt powder residue around the case mouth or even down the length of the case. This is never a good sign. When it happens, it usually happens pretty inconsistently, leading to variations in velocity and the attendant accuracy falloff. If we shoot enough, it will eventually foul the chamber to the point that it may become difficult to chamber and/or extract rounds. I can see where steel cases would lead to more difficulties of this nature. I guess, though, if the chamber is sloppy enough, the gun will keep shooting regardless. That's all we really want in a military small arm anyway. As a civilian, though, I would be looking for better.
And yes, I believe you are correct, in that powder chemistry is not exactly ideal in these rounds either. I bet whatever cheap, produced by the tons for military use powder they use in these is very erosive and corrosive as well. I bet it burns the throats right out of the rifles in which it is used.
They probably still use mercuric primers just to add a little icing on the cake. Cheap to make, but corrosive as hell. All in all, a pretty unholy mix that I don't think I would ever have anything to do with. Maybe if I had some cheap ass surplus sheet metal SKS or something, but I don't see one of those in my near future either. As Townsend Whelen once said, "only accurate rifles are interesting". I prefer "interesting" rifles, thank you very much.