Monday, May 21, 2012

A Bad Day Shooting . . .

Can get pretty bad!

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Couldn’t get any worse than the back end of a shell blowing half off, right?

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I guess it go blow fully off.  But that wouldn’t hurt a big, tough, AR-15, right?

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I checked Bing images, just to be sure, and no, the extractor isn’t actually supposed to be bent back like that.

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Funny story about that PMAG.  The sales girl told me that some of her customers had driven a truck over one and reported that it wasn’t damaged.

I’m not exactly sure what went wrong here.  I originally thought that a round had gone tragically wrong and had lodged itself in the chamber so tightly that it had to be knocked out with a cleaning rod from the muzzle end.  But when several subsequent rounds from different manufacturers also had to be banged out, I eventually took a harder look at the extractor.  And, of course, that magazine, which seemed to have been damaged on the second or third round after the initial problem.

Obviously, the extractor needs replacing, but the shells also seem to be sticking in the chamber, although it’s difficult to diagnose this problem independently of the extractor.

11 comments:

Professor Hale said...

What did you do?

I think you are still under warrenty. Send the whole thing back to the factory for repair or replacement. You may have other defects that you are not qualified to detect.

have you been using that cheap steel case ammo?

Professor Hale said...

For the record, I have never been tempted to run over anything of mine with a truck, just to see if it would survive. I would look suspiciously at claims from vendors about "other people" doing such things.

Giraffe said...

Those rounds must be way hot. Like a mistake was made in a handload.

I've had factory loads blow primers with two different brands, so even factories screw up.

The way the brass was flowing into the extractor slot suggests very high pressure.

You definitely need to stop shooting that batch of ammo.

another possibility, it is supposed to be bad juju to shoot 5.56 nato ammo in a .223 chamber, but I find it difficult to believe it would cause a problem this severe.

Professor Hale said...

Giraffe,
The .223 and 5.56 are compatible in every way. Both have similar SAMMI chabmer pressures. The 5.56 is slightly lower in fact, but required a higher proof pressure. For any ammo you are likely to use or create yourself (other than a complete mistake) you should be fine with either chamber.

I notice that the SSA website says things about their own "hot loads".

Phi, were you using some sort of "special" ammo?

Dr. Φ said...

They were COTS rounds, and I'm embarrassed to say that, although I carefully wrote down which manufacturer it was that made the round that gave me my initial misfire, that particular post got nuc'd somehow, so I can't say for sure, but I think in may have been Cor-Bon. It was most emphatically NOT the lacquered steel, and I only fired about 25 rounds of that anyway.

I'll send the whole thing back.

Kirk said...

"The .223 and 5.56 are compatible in every way."

For the record, if the rifle is 5.56 then yes, it can use both. If it's chambered in .223, then no. I can't imagine an AR being made in .223 though. (And even though that does happen, I can't imagine that being the problem.)

As for the mag, it probably got damaged by the escaping gasses. That pressure has to go somewhere. Ditto the extractor.

Kirk said...

Oh, and it's nice to see another blogger who shoots.

Giraffe said...

The .223 and 5.56 are compatible in every way.

.223 can have a shorter throat. SAAMI spec is a shorter throat but I doubt gun makes actually chamber an AR that way. And 5.56 is supposed to be slightly higher pressure, which wouldn't make any difference except when combined with a shorter throat.

But I wouldn't expect that to cause anything like this. This has to be an overload or bad brass or something like that.

Professor Hale said...

Like I said...Compatible in every way. The small differences in SAAMI spec are not going to be anywhere near the upper limit of commercially available ammo capabilities, or for military grade ammo. Thee is a lot of mythology about neve ever using 5.56mm ammo in chambers stamped for .223, but in fact there is no measurable difference and both types of ammo will work just fine.

The throat differences would only matter in a bolt action gun using hand made ammo where the bullet is seated to make contact with the lands of the barrel. You aren't going to expereience this is in an AR or with any COTS ammo. One reason: The ammo won't fit in your magazine (too long).

Dr. Φ said...

For the record, my AR is advertised as chambered for 5.56.

Professor Hale said...

Advertisements aside, it should have 5.56 stamped somewhere on the barrel (normally between the gas block and the flash hider).