I have .45 ACP and .30 M1 ammo with steel cases. I never cared for it as it stresses the extractors too much. Extraction can already a be weak point with weapons so why compound the problem.
Sorry to say but I can't see the logic in that Brian. The extractor still has to ride up and over the case whether it's made from steel or brass. And it still has to withdraw it too. Or have I missed something in the reading.
No, I agree with that logic but I always felt that brass had a lubricity that steel does not. The M1 Carbine's extractor is not the most robust design in the world either. I know steel casings aren't good for AR type rifles but most of those problems have been cured with the SOCOM mods to beef up the extractor power. Buildup of lacquer in the chamber can be a culprit too if not thoroughly cleaned. Just problems I've seen/cured here as many are using Wolff and other brands of steel cased ammo in quantity. Bear in mind that some don't exactly put weapons maintenance at the top of their priority list either. I don't think steel is a problem with most MG's.
Steel .45 cases have always extracted harder for me as well. Haven't noticed so much with 9x19, but that's probably due to the .45s being in finer tune for various applications, ie. light bullseye loads, Steel Challenge "go fast" loads, full power ammo, etc. Used to reload steel cases quite a bit for the .45 as that's what I had the most about the house.
I think the real virtue of brass cases is it's ability deform considerably before failure. Steel might stretch 10-15% but brass may go 50%+ before it lets go altogether. Seem to remember an article in the back of Cartridges of the World, 8th Ed. (I think!) that covers the brass issue well.
I have to say that it's been interesting for me particularly as it's taught me a lot about the US designs for semi auto Brens. Not just a lot..... but everyhting I know now! A great thread for cross pollination of ideas/thoughts etc
Is your avtar your actual car number plate CSM? I ought to change the '......home of MG cars' part of my logo because we are now being bombarded with adverts for the new type MG cars........... from China! Who ever heard of Morris Garages in China?
Last edited by Peter Laidler; 05-14-2015 at 04:10 AM.
My story regarding steel-cases ammo involves severe damage to a SiG AMT.
The steel-cased Bulgarian? and Chinese 7.62 NATO ammo does NOT "grip" the chamber the same way, NOR does it spring back the same way.
If you ever examine brass cases tossed out of a SiG or a H&K 91, for example, you will notice a series of dark "stains" along the front two thirds of the case. (16 for a SiG and twelve for the H&K).
The brass under these stains is RAISED above the normal fired case surface.
What happens is that the brass starts to "flow" into the flutes in the chamber at peak pressure, momentarily "gripping" the chamber a bit harder, (remember we are talking about "semi-locked mechanisms here).
Then, as the bullet moves up the barrel, the pressure drops enough for the case to "relax" slightly, contract a tiny bit and allow the gas, still at relatively high pressure, to bleed between the case and the flutes, thus starting to "float" the case.
The cumulative rearward forces exert pressure on the front of the bolt assembly. This in turn acts on the "wedge" that holds the rollers in place, and under extreme mechanical disadvantage, forces the wedge, and thus the carrier to move rearwards.
This system was first used on the old German StG 45, VERY late in WW2. It was designed around STEEL-cases 7.92 x 33 ammo.
HOWEVER, unlike the StG 45, the mechanism of the SiG was specifically designed to operate with BRASS cased ammo, first in an experimental job that used a special short cartridge, and then in the Stg57.
The AMT, or at least its "military variant" is just a "NATO-ised" 57, for export.
Firing steel cased ammo in one of these is a recipe for disaster. The steel does NOT "flow" fast or far enough to provide the essential "grip" on the chamber wall, and thus, starts to open too early. The result is that the working parts move rearwards too soon and too FAST, thus damaging the rifle internally. There is also NO guarantee that said ammo is anywhere near the pressure curve and PEAK pressure as specified for "real" NATO fodder. Some will have noticed that our Chinese cousins even made steel-cased "7.62 x 51 NATO" ammo, complete with the NATO "Circle X" mark; not sure who they thought they were fooling.
It is POSSIBLE that a change of "wedge" angle and / or return spring may solve that issue, but who has a couple of "spare" rifles for the experiments?
Remember also that, post WW2, the Stg 45, and designer "retired" to Spain for a little Rest and Re-Development. The result was the CETME series that started out with its own "special" cartridge and moved up to a "mildly" loaded 7.62 NATO case and ultimately went back to Germany to become the G3, firing "full-strength" NATO ammo.
Whilst both the SiG and the H&K rifles use mechanisms derived from the same grand-parent weapon, they are quite different to fire. The recoil of the SiG has a smooth, "rolling" push, whereas the H&K has a distinct "jab".
Back when Oz still had a sense of humour, I had both types and loved them dearly; The SiG for its pleasant and precise shooting and the H&K for its robustness and ability to handle dust and dirt, (and the fact that I had the proper scope for it).
If you own a SiG AMT, (lucky you), "cheap" ammo may ultimately be VERY expensive to use.
Then, as the bullet moves up the barrel, the pressure drops enough for the case to "relax" slightly, contract a tiny bit and allow the gas, still at relatively high pressure, to bleed between the case and the flutes, thus starting to "float" the case.
This marvel of engineering relies heavily on the ammunition, (too heavily in my humble opinion). It must be made just right. Any variance can, and often does lead to the case becoming stuck in the chamber. If the case is annealed too much or too little, or not enough area or too much area is annealed, and heaven forbid you use commercial ammunition that’s not made to the exact dimensions demanded by the engineers. And then there’s the type of powder………
H&K’s fluted chambers are notorious for stuck cases. The Sig’s chamber flutes are not as deep, so it’s a bit more tolerant of different ammunition. But the whole fluted chamber concept adds a degree of complexity that’s not necessary and reliability suffers as a result.
A hard extracting, over gassed long stroke piston gun will run like a top on any ammunition. Yes, it’s crude. There’s no fancy over engineering, just brute force extracting the case. But who can argue with the reliability of the AK and PKM? And while not as over gassed the FN MAG, M1 Garand and the Bren are some of the most reliable guns in the history of warfare.
Some guns are like fancy cars that need high octane fuel or they won’t run right. There’s nothing wrong with cheaper low octane fuel. They are just not made to use it. Putting steel ammo in a Sig or H&K is like putting low octane fuel in a fancy car. If you want burn that stuff, you need something like an F150 pickup that’s designed to run on it.
The Bren was not designed to use steel ammunition, but it operates very much like guns that were and it’s certainly robust enough.
PM
Originally Posted by csmarcher
