Very strange AR-15 failure

[Krupski]

My AR-15 started jamming today at the range. It wouldn't extract a casing despite the fact that the casing was not stuck and easily came out with a light tap from a cleaning rod.

The problem turned out to be that the "lip" on the extractor that hooks the rim of the casing cracked off! (see pic)



I've never heard of this happening to anyone before. I wasn't bump firing or using steel cased ammo.

If you can see it... the crack area is very grainy looking... indicative of VERY hard metal that was brittle. The extractor was a DPMS chrome plated part.

Has this ever happened to any of you?

[TEN-32]

Never had it happen but how many rounds has the extractor seen?

[Krupski]

Never had it happen but how many rounds has the extractor seen?

Not many... probably a few thousand at most.

[stinker]

Looking at the texture of the rest of the part i wonder if that was forged or milled. Drop forged tools that break have that exact same looking texture at the break point. Milled billet is generally stronger is'nt it? Materials quality and process issue perhaps?

I'm just thinking out loud here(so to speak)

[Krupski]

Looking at the texture of the rest of the part i wonder if that was forged or milled. Drop forged tools that break have that exact same looking texture at the break point. Milled billet is generally stronger is'nt it? Materials quality and process issue perhaps?

I'm just thinking out loud here(so to speak)

Don't know how it was manufactured. I purposely bought the chrome plated part so that the hard surface wouldn't wear excessively if I used steel cased ammo. But it seems as though the base steel was way too hard... it looks like a brittle fracture.

Oh well... now I know to carry a spare extractor in my range box. Maybe I should carry spares of all the little parts.......

[Oswald Bastable]

Oh well... now I know to carry a spare extractor in my range box. Maybe I should carry spares of all the little parts.......

Or you could just carry all AK and not worry about "little" parts causing problems.

[AK-J]

One of my SAR2s had the same thing happen with its extractor.

[Schuetzenman]

Looking at the texture of the rest of the part i wonder if that was forged or milled. Drop forged tools that break have that exact same looking texture at the break point. Milled billet is generally stronger is'nt it? Materials quality and process issue perhaps?

I'm just thinking out loud here(so to speak)

Actually no forged metal is stronger becasue it folds and bends the grain of the steel. Milled steel is only of one grain orientation unless of course it was a milled forging. The grain shows that it is a hard metal, perhaps too hard. If the inside of the extractor hook was a dead sharp 90° angle this would be a stress concentrator. Hard metal, really any metal should have either a radius or a chamfer at an inside corner like that to prevent the stress and break point. IF it did have the rad or cham and it still broke I would definitely say it was overly hard and therefore brittle.

For the record I have heard of extractors breaking, but not sure if it's just the hook or further back. It is one of the reasons why a person should have a complete ready to drop in bolt on the weapon. It can be changed out very quickly in the field (the bolt head).

[abpt1]

Actually no forged metal is stronger becasue it folds and bends the grain of the steel. Milled steel is only of one grain orientation unless of course it was a milled forging. The grain shows that it is a hard metal, perhaps too hard. If the inside of the extractor hook was a dead sharp 90° angle this would be a stress concentrator. Hard metal, really any metal should have either a radius or a chamfer at an inside corner like that to prevent the stress and break point. IF it did have the rad or cham and it still broke I would definitely say it was overly hard and therefore brittle.

For the record I have heard of extractors breaking, but not sure if it's just the hook or further back. It is one of the reasons why a person should have a complete ready to drop in bolt on the weapon. It can be changed out very quickly in the field (the bolt head).

Id disagreed the fact that forged is stronger. I think milled is less likly to crack or break because

Milled steel is only of one grain orientation

[mrkalashnikov]

I carry a complete spare AR-15 bolt for such emergencies.

[NAPOTS]

Seeing as how you bought the chrome plated bolt I wonder if you have an issue with hydrogen embrittlement.

[5.56NATO]

Was this a shorty ar?

[circuits]

While not common, I've seen two such failures in the last 15 years, none on my personal rifles.

[mriddick]

Could you of had a case failure and not known it? Those have been known to break extractors and who knows if already into the extraction process could of dumped the offending casing without you noticing.

[Krupski]

Seeing as how you bought the chrome plated bolt I wonder if you have an issue with hydrogen embrittlement.

Interesting thought. Maybe plain old steel parts are better in the long run... ?

[Krupski]

Or you could just carry all AK and not worry about "little" parts causing problems.

Good point!

[Krupski]

Was this a shorty ar?

Yes. A 16 inch carbine.

[Krupski]

Could you of had a case failure and not known it? Those have been known to break extractors and who knows if already into the extraction process could of dumped the offending casing without you noticing.

Possible... what kind of case failure would break an extractor?

And you're right... I would have never noticed it or found a bad casing.

When it started I first thought "bad mag". So I changed mags and had another jam... so I thought "bad ammo - stuck case".

After knocking a few out with the cleaning rod I noticed that they came out very easily, so I tried to pull one out by racking the bolt.

The charging handle came back easily (barely grabbed the shell rim at all) so I thought "bad spring on the extractor".

I pulled out the bolt, removed the extractor and looked at the spring. Spring was fine... then I noticed the lip was cracked off.

"Oh well... no more AR for today" I said, put the bad extractor back in, reassembled the rifle and put it away.

By then, quite a few "bad" cases were on the ground and I never even thought to look at any of them.

That's one way to save $$$ on ammo, huh?

[Krupski]

I carry a complete spare AR-15 bolt for such emergencies.

I may do that (or carry a little bag of spare parts).

[mrkalashnikov]

I may do that (or carry a little bag of spare parts).

A friend who is BIG time into AR building recommended that to me a couple of years ago, in place of fiddling w/ broken extractors, ejectors, gas rings, etc while "in the field". I got a complete factory bolt from Armalite for my M15A2 for a little over $70. Well worth it imo.

You can do overhaul repairs once you get back home & swap bolts back then.