Steel Ammuntion? In my AR?

[tower59]

Totally not the professional gunner here, but at every AR class I've attended, the folks who have frequent jams and failures are shooting Russian steel ammo. It left a solid impression with me. I would be interested to hear from people who run these classes who watch a hundred or more shooters per year and see what their observations are regarding ammunition choice.

[DirectTo]

I love the lengths cheap people will go to defend their cheap decisions.

While I'd never use it for serious shooting, it's more than adequate for blasting away at the range. The price difference will cover replacement of even the nicest barrels.

I've quit caring what I grab for range days. More shooting is better, period.

[T2C]

I love the lengths cheap people will go to defend their cheap decisions.

At a cost savings of over $1,000 per year, I shoot quite a bit of steel case .223 ammunition. I replace the barrel on a given carbine once every 18 months or so, so the savings adds up.

I've seen improperly maintained carbines puke on 80g match.

[t15]

I believe the wolf polyformance WPA is from the Barnaul plant.

[lysander]

A couple of points here... (edited for brevity)

[clip]
Instead, dirty chambers cause cases to stick - and because steel isn't elastic in the same way as brass, the steel cases don't obturate the chamber as well as brass cases do, which leads to soot and gunk accumulating in the neck area of the chamber.

[clip]
Finally, let's talk alloys. I have no idea what specific steel alloy is used in cartridge cases, but steel can be almost soft enough to scratch with a fingernail or hard enough to cut other steels like butter. In other words, "steel" is the name for a HUGE range of metals whose only commonality is that they are iron based and include carbon... Brass cartridge cases are usually made with a particular alloy called "cartridge brass," which is 75% copper and 25% zinc. This gives this specific alloy specific properties, such as elasticity, malleability, etc. Why would steel for cartridge cases not also be specific? (I'll also point out that traditional bullet jackets are made of "gilding metal," which is a brass alloy of 95% copper and 5% zinc. Traditional jackets are NOT "copper" or they would turn green and erode pretty quickly...)

Actually, steel cases obturate just fine.

At 50,000 psi the sides of a steel case are stuck against the chamber walls as well as any brass case. The difference is at what pressure the case fully expands to achieve the seal.

The bullet uncorks from the case neck when the pressure inside the case is about 900 psi, brass or steel. As soon as it uncorks, gas will start to flow around the case into the chamber bringing all the dirty combustion products with it. How fast the case neck inflates to seal this flow off depends on a number of things, but mainly, 1) how fast is the pressure rise inside the case, and 2) how resistant is the case neck is to distortion.

Stuck cases are probably far more likely caused by improper heat treatment of the steel. Otherwise all steel ammunition would start to show FTE after a certain number of rounds, which is not the case, they tend to occur at random.

As to lacquer causing problems, all US produced steel cased ammunition, mainly 25mm, uses lacquer as a corrosion preventative. However, and this is a big however, 25mm product testing has shown that the wrong choice of lacquer will cause problems. Is it out side the realm of possibility that some lots of Russian ammo where made with a poor choice of lacquer? No, I don't think so. But again, it's the generalization that is wrong - lacquer = bad, no, more correctly it's poor quality control = bad . . .

As to the alloy used, almost everybody that has ever made cases from steel has used a mild steel alloy, 1025 or 1035, maybe 1040 or the local equivalent. One, it's cheap, and that was the whole point of steel cases in the first place. And two, it has a strength similar to cartridge brass. Many people think that steel cases are much stronger than brass, they are a tad stronger at the rim, but not really enough to really make much difference.

And, here is where we are going to refer back to the obturation thing. The neck of a brass case is fully annealed (or it should be) so the the yield strength is 45,000 to 60,000 psi. Any guesses to the yield strength of 1035 tempered to about HRb 60 to 70 (what Frankford found to work best)? Yeah, it's around 40,000 to 50,000 psi.

The resistance of the case neck to distortion is about the same for brass and steel cases, so they obturate just as well and, for the same pressure curves, just as fast. The reason Russian cases are dirtier on the outside is the probably due to the propellant they use.

There has been a big change in Russian produced ammunition that has changed the whole barrel wear thing, however. They, at least Tula, have stopped cladding the jacket with gilding metal. It might make a significant difference with .224 bullets. Generally, the cladding was .003" thick, which is about the same as the depth of the lands. The cladding did provide some lubricity similar to regular GM jacketed bullets.

[MWT]

Great info lysander.

My recent experience with Silver Bear comes from a friend I attended a carbine course with who had failures to extract from the chamber of his two Stag mid length's once it warmed up. Had to be beaten out with a cleaning rod. I on the other hand really like Hornady Steel Match and stock up whenever it's available. Best of both worlds, cheap steel cases with Hornady powder and bullet. Really accurate stuff too, I found it to be on par accuracy wise with the regular brass Hornady 55 HP load in my PWS Mk114.
The older batches of Hornady Steel Match used rougher polymer coated cases and I once had a Lancer L5AWM magazine jam when it was dirty inside. Never happened with brass or lacquer.

[abso]

Actually, steel cases obturate just fine.

At 50,000 psi the sides of a steel case are stuck against the chamber walls as well as any brass case. The difference is at what pressure the case fully expands to achieve the seal.

The bullet uncorks from the case neck when the pressure inside the case is about 900 psi, brass or steel. As soon as it uncorks, gas will start to flow around the case into the chamber bringing all the dirty combustion products with it. How fast the case neck inflates to seal this flow off depends on a number of things, but mainly, 1) how fast is the pressure rise inside the case, and 2) how resistant is the case neck is to distortion.

Stuck cases are probably far more likely caused by improper heat treatment of the steel. Otherwise all steel ammunition would start to show FTE after a certain number of rounds, which is not the case, they tend to occur at random.

As to lacquer causing problems, all US produced steel cased ammunition, mainly 25mm, uses lacquer as a corrosion preventative. However, and this is a big however, 25mm product testing has shown that the wrong choice of lacquer will cause problems. Is it out side the realm of possibility that some lots of Russian ammo where made with a poor choice of lacquer? No, I don't think so. But again, it's the generalization that is wrong - lacquer = bad, no, more correctly it's poor quality control = bad . . .

As to the alloy used, almost everybody that has ever made cases from steel has used a mild steel alloy, 1025 or 1035, maybe 1040 or the local equivalent. One, it's cheap, and that was the whole point of steel cases in the first place. And two, it has a strength similar to cartridge brass. Many people think that steel cases are much stronger than brass, they are a tad stronger at the rim, but not really enough to really make much difference.

And, here is where we are going to refer back to the obturation thing. The neck of a brass case is fully annealed (or it should be) so the the yield strength is 45,000 to 60,000 psi. Any guesses to the yield strength of 1035 tempered to about HRb 60 to 70 (what Frankford found to work best)? Yeah, it's around 40,000 to 50,000 psi.

The resistance of the case neck to distortion is about the same for brass and steel cases, so they obturate just as well and, for the same pressure curves, just as fast. The reason Russian cases are dirtier on the outside is the probably due to the propellant they use.

There has been a big change in Russian produced ammunition that has changed the whole barrel wear thing, however. They, at least Tula, have stopped cladding the jacket with gilding metal. It might make a significant difference with .224 bullets. Generally, the cladding was .003" thick, which is about the same as the depth of the lands. The cladding did provide some lubricity similar to regular GM jacketed bullets.

Interesting thread, didn't expect so much technical detail.

So, anecdotally, the only problems I've ever had with steel cased ammo (and I've used Wolf Polyformance, Silver Bear, and Tula) has been out of rifles with 5.56 chambers. Long story short my Dad's PSA 5.56 (he's not a serious shooter) and my Cold 6920 have both had stuck cases with Tula - same case of ammo. The cases were so stuck we resorted to pound them out with a cleaning rod. That same day, I had a another rifle with a Rainier Arms .223 Wylde barrel that ate the same Tula up. Between the 3 rifles, we probably shot 500 rounds that day, mainly just blasting steel targets at various distances. Anyone want to guess if its pure luck/maybe bad heat treatment on that case of Tula, or is it due to the different chamber dimensions between the 5.56 chamber vs the .223 Wylde chamber. That's the only time I've ever had issues with steal ammo - though most of the time I'm shooting a rifle with a .223 Wylde chamber.

As an aside, I haven't really bothered to shoot steel since ammo has returned to shelves a couple years ago.

[lysander]

And, just to add, given the properties of steel compared to brass, mainly the elastic properties, brass cases should inflate to fully seal the chamber at around 15,000 to 18,000 psi, steel requires about 30,000 to 40,000 psi. That equates to a time difference of about .07 ms, or 0.0007 seconds.

Also, the hardness of the case head is not super hard on a steel case, compared to a brass case. Generally, the rim section of the case for a brass 7.62mm NATO is listed as 180 to 220, for the experimental steel case Frankford worked up in the early 1970, (and I can’t imagine the Russians doing things widely different) the rim section was listed as 240 to 280.

[T2C]

Thanks for the scientific explanation Lysander.

[lysander]

How about stainless steel?