Case Failure...What happened?

[Death from Afar]

Team, I have been racking my brain on this and just don't really know what caused this. I would be interested to see what you all think.

The Rifle: Ruger 10/22, Whistlepig Barrel, Timney Trigger, BX 25 Magazine.

The Ammo: Federal Bulk Pack Auto Match.

The Situation: A girl I have been teaching to shoot had fired a 25 round magazine of the Federal bulk pack stuff, then changed magazines and fired another 24. At the last round in the magazine- KABOOM. The case had failed, and the side of the case blew out in the direction of the extractor. Luckily no one was hurt, the rifle was undamaged, although a projectile was stuck in the barrel just past the chamber.

So what caused this? My views follow in brackets:

1/ Cook off? ( No the rifle really was not that hot);
2/ Firing out of battery (Impossible with a 10/22 I think);
3/ Round firing as the bolt stripped it out of the magazine ( I have fired uncounted rounds of .22 and never struck this);
4/ Double charge of powder (What are the chances of that?)

So I am baffled. Truly baffled. Any ideas? ( I didn't keep the case as I was ensuring the girl was OK as she had brass all over her hands).

 

[Mobuck]

#2 if the bullet is stuck in the barrel.

 

[snolden]

Firing pin channel dirty or debris on the shoulder could cause an out of battery like said above. Probably a combination of both. .22's are well designed and strong once inside the chamber.

 

[The Big D]

I agree it had to be out of battery. Not sure how it happened, but if it's in battery the bullet goes down the barrel.

 

[FrankenMauser]

Fired out of battery.

The case got hung up in the dirty chamber, or on a piece of brass left by a previous, defective cartridge. At that point, either the bolt or the extractor crushed the rim enough to set off the priming compound.

 

[JohnKSa]

The case had failed, and the side of the case blew out in the direction of the extractor. Luckily no one was hurt, the rifle was undamaged, although a projectile was stuck in the barrel just past the chamber.

Are you sure it's not two projectiles?

From the description it sounds like the round just before the Kaboom was a squib and the second round went overpressure by a lot when the bullet couldn't get down the bore due to the obstruction.

 

[Regular Joe]

The previous round could not have cycled the next round into the chamber if that was the case.
I've had a case failure with a 10/.22 before. Just one, in 50 years of shooting 10/.22's. It happens, though almost never. The gun is OK. The people are OK. Have a beer.

 

[Slamfire]

It is surprising that rimfire cartridges don't have more frequent out of battery slamfires. The priming compound is in the rim and that rim gets bumped and dinged in semi automatic mechanisms. Given that priming compound varies in insensitivity, and varies a surprising amount, incidental rim contact with anything could ignite the priming compound. Don't fool your self into thinking that the bolt face is not hitting the rim, or that slamfires are only caused by firing pin contact.

Primers and priming compound are not predictable. Well at least not 100% predictable, the stuff is a mixture of compounds, if a bit of the batch is not well mixed, maybe some clumping, that would change the sensitivity.

Anyway, glad the Ruger protected the shooter from brass particles and gas escape. Always wear your shooting glasses, even if using those tiny rimfire cartridges and be aware of what your muzzle is pointing at.

Primer goes off in a Purse!

http://news.yahoo.com/blogs/sidesho...ide-woman-purse-shoots-her-leg-232052308.html

By Eric Pfeiffer, Yahoo! News | The Sideshow – Tue, Jun 12, 2012

A Pennsylvania woman was shot in the leg while shopping at a local department store on Tuesday. But in a nearly unbelievable twist, no gun was involved. Apparently, the woman was carrying the bullet in her purse, when it mysteriously exploded.

"She did not have a gun in her purse or on her," Montoursville Deputy Police Chief Jason Bentley told the Williamsport Sun-Gazette. Bentley said the woman, whose name has not been released to the public, "was not aware" she was carrying two or three bullets inside her purse at the time of the accident.
The 56-year-old woman was taken to a local hospital and was eventually discharged. In fact, the woman initially declined medical treatment, only heading to the Williamsport Regional Medical Center after her son reportedly encouraged her to do so.

"Something must of hit the primer of one of the bullets," Bentley said. "The bullet stayed in the purse, but its casing put a hole in the purse and caused a minor leg wound."

Bullets exploding outside of a gun are a rare occurrence but are not entirely unprecedented. In March, a bullet being used as evidence in a court case exploded in a bag and shot 20 feet across a courtroom. No one was hurt in the incident. It was surmised that the bullet exploded after its tip bounced against another bullet tip in the same evidence bag, according to the Telegram & Gazette.

 

[tangolima]

It is not that scary really. The rim needs to be pinched, not only struck, to ignite. That means when the firing strike the face of the rim, the back of rim needs to be supported by barrel breech. All that has to be done with speed. That's why guns with dented breech may misfire.

The rifle might have out-of-battery ignition, or a case blow out at the extractor cut out, where chamber support may had been compromised. Inspection on the brass remain will give some clues.

Having said all that, it is rather unwise to keep cartridges in purse. Lead Will rub off from the bullets. That alone is bad enough.

-TL

 

[mete]

Never have batteries [unless in containers ] in your pocket with loose ammo ! That has caused firing of ammo

 

[Tjohn]

It could have been simply some inperfection in the case, that happens from time to time. It was not likely a cook off if that is all that had been fired, two 25 round mags right? The barrel would have been fairly warm but shouldn't have been hot enough for that. Possibly as someone else said there could have been a squib round immediately before it.

 

[Mike38]

The previous round could not have cycled the next round into the chamber if that was the case.

About ten years ago, I had a .22 squib in a semi automatic handgun (Baikal IZH35M) that the bullet stopped about 3 inches forward of the chamber, and a follow up shot pushed the stuck bullet as well as the second one out the bore. So, the squib must have had enough power to cycle the action otherwise the follow up shot would not have been possible.

Luckily, the only problem that came out of my experience was a badly leaded bore. The two bullets smeared their way down the bore. I cleaned it good and still shoot this firearm today.

 

[m&p45acp10+1]

A squib can very well cycle the action of most .22 LR semi auto actions. I had it happen with a 597 Remington years ago. My hearing is not very good at all. If it had not been for a friend with me. I would have fired the next round. It was in full battery, the bullet was a few inches ahead of the chamber. I was careful after that. It happened two more times in the next 100 rounds. I disposed of the brick of ammo after that. The ammo was old stuff anyway. All 3 squibs had the round after chamber.

 

[bfoosh006]

I also suspect a squib round... you should run a tight patch down your barrel and check for a "Bulge"... you will feel it readily.