Sunday, May 20, 2012

The AR-15 and steel cased ammo - how to make Wolf or Tula shoot reliably.

We've all been there...walking around the local gun store (or, as I like to call it, the Magic Goody Shop) and seen Russian-made steel cased .223 ammo selling for quite a bit less than the brass versions of the same rounds.  And, many of us have fallen to temptation and bought scads of the stuff, thinking of how much money we'll save, and how we can plink 'til our heart's content for pennies on the dollar.

And then, many of us have faced the bitter disappointment of repeated malfunctions and losing money when we give away a large pile of ammo that simply won't function properly in our guns.

I've seen quite a few stories of people trying to shoot steel cased ammo out of an AR-15 rifle with less than satisfactory results.  The most common issue is the dreaded "stuck case", where the case wedges itself so firmly in the chamber that the extractor simply doesn't have the "oomph" to move it.  In fact, most often, the only remedy is to put a cleaning rod down the bore of your gun and whack it with a hammer.

That's what I had to do.  My AR was particularly finicky, barely firing 50 rounds of Wolf or Tula before hanging up completely, bringing an early ending to a day at the range.  The thing would run like a champ all day long on brass, even crappy brass, but a couple boxes of Tula would bring it to its knees.

I began reading about this on the Internets, and it is a common problem.  Many have the completely WRONG idea about what causes this, however.

First, it is NOT caused by a "lacquer coating" cooking off and leaving its residue in the chamber.  If you don't believe me, get a spent shell and hit it with a blowtorch.  Nothing's coming off of that sucker.  If you've bought your ammo in the past few years, it doesn't even have lacquer on it.

Second, many people believe it is because the steel expands, and, being less flexible than brass, wedges itself in the chamber.  That's not true either.  But, steel being less flexible that brass does contribute to the problem.

The answer is simpler (and fortunately more correctable) than either of those.

Steel doesn't expand like brass does in the chamber.  This allows a slight gap around the cartridge case upon firing.  That gap admits powder residue and carbon into the chamber, which begins building up on the sides.  Pretty soon, the dimensions of the chamber are too small to allow the casing to move freely in and out.  The next time the bolt slams a round into the chamber, it wedges there, unable to be moved without physical intervention.

"Well," you might say, "the 7.62 x 39 rounds that I shoot are steel cased, and they don't have that problem".  No, they don't.  But, it is not because the blowback of residue into the chamber isn't happening.  It is because of the shape of the round itself.  The sides of the 7.62 x 39 are tapered enough that they can still overcome friction with the sides of the chamber.  The .223 is far straighter, and so it is far more difficult for the extractor to overcome the frictional forces of the now smaller chamber that has a good hold on the straight walls of the shell case. 

This is the problem I had with my rifle.  On multiple occasions, always after firing less than 50 rounds of steel cased ammo, I have had a major stoppage with my AR.  It always involved a spent case hanging up in the chamber, it always was impossible to clear without jamming a cleaning rod down the barrel and knocking it out, and it almost always put my AR out of action until I could take it home and work on it.

Once, while in the presence of a buddy of mine, I experienced the problem and he said, "You need to run a little brass in every mag to keep it cleaned out."

That didn't make sense to me.  How did brass keep the action clean?  Besides, common knowledge was that you never mix steel and brass when shooting...that mixing the two would only make this problem worse. 

Then I read this article on the Box O' Truth about steel case and brass cased ammo.  Although their hypothesis confirmed my friend's statement that brass ammo could help clean the chamber, they stopped short of recommending (or figuring out) that running steel and brass together can make a gun run more reliably.

I figured it was up to me to test it.

I started by cleaning the chamber thoroughly and soaking it down with CLP.  I then loaded my mags with one round of brass case for every 9 of steel.  Then, I headed to the range.

Fully expecting to get a stoppage before the end of mag number two, the AR kept eating the steel case well past that point.  The brass coming out eventually carried a considerable amount of black deposit on the outside of it.  It was rock hard and couldn't be scraped off with a fingernail. I did a variety of shooting, including slow firing (shooting once every 20 seconds or so), sustained slow firing (shooting once every five seconds),  fast firing (shooting as fast as I could pull the trigger) and even some bump firing (near automatic rates of fire).

The AR had two hiccups, probably attributable to the Russian ammo's lower power.  On the first, the round didn't quite come all the way out of the mag.  I gave the bottom of the mag a whack and it kept going.  The next, the bolt didn't appear to come back far enough to grab the next round.  A quick pull of the charging handle fixed it. The gun seemed to run fine otherwise, and most importantly, no casings were getting stuck in the chamber.  After five mags and nearly 150 rounds, I was running out of time and would be late for another engagement, so I packed it up to continue testing later.  Besides, the gun showed no signs of slowing down.  I was satisfied.

I have seen other options recommended, such as changing uppers or barrels to get a chromed chamber, or using a chamber reamer.  Both would probably work, but for the occasional use of steel cased ammo, both seem to be overkill. A 100 round box of cheap brass cased ammo should let you shoot 1000 rounds of steel case, if this method works for you.  You might even be able to tweak the ratios and get away with 1 for 20 or 1 for 30.

If you have an AR that doesn't like steel ammo, but have a stockpile of it or have a source where you can get it for cheap, it's worth a try to mix some brass in with the steel and see if your AR will run it.


Anonymous said...

nice posting.. thanks for sharing.

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