The use of steel cased ammunition is hotly debated on web forums. The concept has been around since World War 2, but the controversy is far from over. Originally used to combat brass shortages, steel cases actually have a couple of important advantages. Let’s cover the disadvantages first. Steel cases don’t spring back as well as brass and aren’t effectively reloadable. They require plating with zinc or copper, or else a coating of polymer or lacquer to resist corrosion. Some people feel that even mild steel is harder on the extractors, and that is almost certainly true. However, the alternative to the increased extractor wear with steel cases is the increased likelihood of failure to extract because of a torn brass case rim in certain firearms. All in all, I used to view steel cased ammunition as something to avoid until a friend acquired a .223 FAL rifle. That’s right, an FAL built on an aluminum receiver in .223 — light, handy, able to use AR15 magazines (quite an advantage during the AWB years) but also non-functional. The extraction cycle was so violent that case head separation was routine and completely tied up the gun every few shots. The problem was solved by restricting that carbine to a diet of steel cased military surplus and the problems stopped. The extraction was still quite violent, with cases flung 15-20 feet away from the gun, but the stronger cartridge cases held up just fine.
Gas-operated rifles like AR15 use straight walled cases and extract relatively gently. Most of them will still run with steel cased ammunition, but in marginal cases the extra friction of polymer-coated .30 carbine, .223 or .308 case can be detrimental to the reliability. Rifles chambered for 7.62×39 Russian, 5.45×39 Russian and 6.8SPS don’t have that problem because of much greater case taper. Russian AK rifles and others with massive bolt carriers also have considerable reserves of extraction power to un-peel even a stubborn case from the chamber. The same issue comes up with 45ACP gas-operated BAZ45 — it won’t run with steel cases while blowback operated carbines and pretty much all 45ACP pistols work just fine. The tradeoff is, of course, felt recoil. A blowback 45ACP carbine kicks considerably more than BAZ45 fired with full-power brass cased cartridges. It’s the same with rifles — a 20″ AR15 is actually less likely to work well with steel cases than shorter guns with more rapid cycling, at the cost of more wear and tear on the shorties. Delayed blowback rifles, such as G3 and FAMAS, actually benefit from steel cases because their ejection cycles are fairly violent and hard on the brass. PTR91 is therefore a very economical rifle: not only can you buy 20-round magazines for it for under $2, but it also thrives on inexpensive fodder.
During WW2, United States Army used steel cased 45ACP ammunition. It was an austerity measure, but it was discovered that even steel cased cartridges can work quite well when properly loaded, polished and used in accurate firearms. There’s nothing inherent in the case material that would make such ammunition less accurate, other than the tendency for steel to be used in budget lines with less stringent QC. Hornady proved this point with their Steel Match line designed for competition use. By loading accurate ammunition in steel cases with simple bullets bullets, they provide an economical choice for people who do not reload and do not require exceptional terminal performance typical of hunting and defensive loads. And that brings us to the other advantage of steel cases: for the same amount of money, a shooter using steel ammunition in compatible firearms can get 50% more trigger time than the shooter using brass cased ammo. If the price of ammunition is a consideration in your training, this can be significant. Verify that your guns run with steel case cartridges before stocking up, but don’t be surprised if they work just fine.