The Truth About Steel Cased Ammunition

As a small arms instructor and range safety officer, I frequently see AR platform rifles lock up using steel cased ammo. Many think it is due to lacquer or ploymer on the case to prevent rust gumming up a hot chamber. But is that really the reason? And will steel cased ammo really damage your AR?

800px-7.62x39_-_FMJ_-_2There are two “accepted” points of view in regards to shooting steel case ammo in AR platforms rifles. The first is that it will damage the chamber and extractor, and the second is that stuck cases in chambers are the result of lacquer coating on the cases getting hot, and sticking to the chamber walls. Since I don’t run the AR platform, preferring the AK, I never really paid a lot of attention to these issues until recently. However, I had always wondered about these issues since steel cased ammo has been used for a long time around the world, so I decided to do some research as I plan on buying an AR platform rifle for business purposes. The Germans began using steel cased ammo at the beginning of WW2 due to difficulty in securing enough copper to make brass. It was also lacquer coated to prevent rust on the cases. This ammunition functioned perfectly in their weapons from climate extremes of North Africa to the frozen Russian front. Nor did they seem to have a parts breakage or wear problem using it.So lets look at the two issues separately.

Abnormal Wear and Breakage

To me, this is pretty simple. Wear is a function of a harder surface contacting a softer surface. The steel used in steel cased ammo is a pretty soft steel while the steel used in rifle barrels and parts is much harder. I honestly do not believe that running steel cased ammo through your AR is going to cause any extensive additional wear or damage.

Lacquer or Polymer Coating Gums up a Hot Chamber Causing Cases to Stick

The problem primarily seems to be using Wolf manufactured 5.56mm cartridges in AR series rifles. I have shot a tremendous amount of steel cased, lacquer coated  7.62×39 and 5.45×39 ammo through Aks and CZ-58s to where the barrels were hot enough to light a cigarette on, and after inspecting the spent cases, the only damage I saw to the lacquer was the scratches caused by ejection. The lacquer showed no signs of melting and coming off the case. In addition, Wolf no longer coats steel cases with lacquer, having switched to a polymer coating, yet Wolf manufactured (and others) steel cases still will lock up in AR rifles. So what gives? There are a number of concurrent issues involved.

To understand whats going on here, you have to understand the different characteristics of steel and brass cartridge cases. When a cartridge is fired and the pressure builds inside the case, the case wall expands against the chamber forming a seal preventing the gas from flowing back inside the action. Brass is much “springier” than steel and expands better forming a better seal. Steel cases often do not expand as well, and allow a certain amount of gas back into the chamber causing an increase of carbon build up in the chamber. Then, when a cartridge does expand properly, it can lock in the chamber due to excess carbon.This is not a problem with weapons designed around steel case ammo such as the AK series weapons with looser chamber tolerances, but with most AR’s the tolerances are tighter and this increased carbon build up is a factor.

I volunteer often as a range safety officer at the range I teach at, and every time I have seen a steel case lock up in an AR chamber, there was one common denominator: The rifle was bone dry with no lubricant, and extremely dirty. Many new AR owners are not aware of the lubrication required on this rifle, especially the bolt carrier group, and shooting them bone dry can be a serious factor in malfunctions, including stuck cases. You should use a good quality synthetic lubricant.

If you want to read a really good article about a serious test between steel and brass case ammo, check out this article on Lucky Gunner.

Bottom line?

  1. Steel case ammunition will not wear out your AR faster than brass case ammunition.
  2. It is not lacquer or polymer coating on steel cases that is causing stuck cases. It is the increased carbon build up with steel case ammo.

So if you are running an AR series rifle and want to take advantage of the cheaper steel case ammo, what do you do?

  1. Keep your rifle clean. You should give it a good cleaning every 500 rounds or so.
  2. Keep your rifle well lubricated.

You may find that your particular AR will simply not efficiently digest steel case ammo in which case you will need to feed it brass cased rounds or another option such as zinc coated steel.

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51 thoughts on “The Truth About Steel Cased Ammunition

  1. Pingback: Notes on Keeping Your AR Running | Azweaponcraftprepper

  2. Great article, it looks like you are an expert in the field of armament and maybe you already do a lot of research on weapons, do you think what kind of weapon the best current and are made in which country?

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  3. I am a Police Shooting Instructor in Malta Europe and we run our training with Berdan steel rounds for our Glock’s. We always use the same weapons for training and you can imagine the wear the pistols under-go. I am impressed how steel case eat the chamber when it seats from the magazine to chamber. You can just open the slide and look at the barrel and watch the chamber curved. I suggest brass is the better solution.

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  4. Good informative article about steel vs. brass cases.
    Keep in mind lots of steel cased ammo might have steel in their slug, and I think it will wear out a barrel sooner. (use a magnet to check it out)
    I know from experience steel cased ammo dirtys my action quicker.
    To be sure there is a difference in cost – but from a reliability standpoint – I prefer to use brass and lead instead of steel. It always works –

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    • Carbon has always been a problem with the AR gas system. The original problems with the M-16 in Vietnam were the Army insisting on a ball powder that carboned up a lot more than the flake type currently used (as well as a lack of cleaning kits). I am currently researching the steel in the bullet issue and will peobably do an article on it in the near future. Thanks for your post.

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    • I always knew that 5.56 military brass tends to be thicker than .223 civilian brass, which is a consideration in reloading, I just wasn’t aware that there were actual chambering differences. Thanks for the post!

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  5. I have thousands of steel case rounds through my AR, I buy cases at a time and I regularly even up shooting a case at a time at the range. I have never had a stuck case and the only thing I had to replace was an extractor and that was my fault I dropped the bolt and carrier on concrete while I was cleaning it.

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    • If your AR runs steel good, that’s great! I suspect that you know your weapon inside and out and keep it clean and lubed. A lot of AR’s digest steel O.K. Luck of the draw maybe. Sort of like women. Some work out. Some don’t.

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    • It’s the same cartridge, .223 being the civilian designation, 5.56mm being the military. Since doing the research for this article I discovered that there seems to be a difference in chambering dimensions some how. Since I don’t run AR’s I will have to study this in more depth. Perhaps other readers can explain more.

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  6. It really seems to depend on the manufacturer and the tolerances of the platform. My mini 14 doesn’t even balk at steel cassed ammo, and I have a lot of wolf ammo for practice ammo. My ar-10 will eat it for a while and then start having problems, hence your observations. As it dirties up problems start. The same with my handguns. My 1911, no problems, my bursa’s big problem. I’ve also found that steel also has a magazine feed problem too.

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  7. Another question would be the difference between the .223 and the 5.56 chambers on how the steel would react. Not all ARs have the same chambers.

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    • My research on this subject led me to see that there actually is some sort of difference in chambering between .223 and 5.56. I am going to have to research this more, but it does seem to matter.

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      • The military 5.56×45 (NATO) specification allows the mil-spec ammo to produce more pressure (although it usually does not) than the 223 REM commercial rounds SAAMI specifications allow. You should not shoot 5.56 Nato in a gun that is chambered for 223 REM as the pressure could be more than the gun is designed for. Conversely the 223 Rem is safe to shoot in the 5.56 Nato chambered gun. The throat of the chamber is usually longer in a 5.56 vs 223.

        Cleaning does matter, but some guns with tight chambers still have trouble with steel cases even when everything is clean and lubed. Because the steel case does not contract back to near its original size like brass it takes more force to remove the steel even when clean. The extractor on the AR15 pivots near its center and relies on a spring at the rear to apply the grip pressure at the lip of the case. The problem occurs when the force to remove the case is greater than the pressure applied by the extractor spring and the extractor slides off the lip leaving the case stuck in the chamber.

        We have addressed this with our guns by increasing the spring rate of the extractor spring. Not only does this allow the gun to shoot steel cased ammo it also makes extraction of brass more reliable. You can do this to your AR with a extractor spring from Wolff Spring. It takes 5 minutes, costs $3, and does not require gun smithing. Here’s a video link shooting steel. http://mcduffeearms.com/wp/videos/

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  8. Love my AR it eats through steel case without fail. I kept getting the warnings you debunked. My thoughts on them were if it jams I’ll do a malfunction drill, I only use brass case when using it for protection or hunting where I do all I can to avoid possible malfunctions.

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    • Knowing your individual weapon is important. Malfunction drills are important, but all of the stuck steel cases I have seen required a cleaning rod to beat them out of the chamber. Not a happy situation in SHTF.

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