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Case Rupture - What caused this?


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Shot my first PRS .22 match yesterday with my squirrel gun.  Ruger wooden 10/22 stock except it has a CST Tech Grand Master match trigger and bolt.  

Last round in the string, I fired and it was much louder.  Checked the chamber and the bullet was sticking half way sticking out of the barrel.  Could see a piece of brass near the breach and some balls which I assume was unexploded ball powder which was unexploded for some reason all around the chamber and on the bolt face.  Couldn't find the case until I ejected the mag and saw that it was in the magazine, ruptured.  

 

Was able to knock the round out of the barrel with a cleaning rod and I proceeded to shoot the match.  Blew out the chamber and had no further issues.  

 

Ammo was Black Box Match Eley.  

 

What caused this and do I need to be concerned?  Anything I need to check?

 

Thanks!

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Are you sure the case in the magazine was the case that ruptured?  Does it have a firing pin mark?  If not, it was blown open by the case that had an out of battery rupture and all the unburnt powder is from the unfired case in the magazine.

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Good question!!!  It does have a mark on the rim but it looks a little light to be from the firing pin.  HOWEVER, the brass inside is clean, showing no signs of burnt powder which seems to line up with what you are saying Ming.

A bit more information.  This was around shot 30 in the match.  Prior to this, twice I had rounds that failed to feed and the brass was dented.  Also, temperature was around 20F, but I was keeping the rounds and the magazines in my pocket with a handwarmer prior to shooting.  Also, my rifle was cleaned before this shoot.  

 

Will the rifle fire that far out of battery?  I might test that.  I would think with the bullet halfway stuck in the barrel that it would have had to have been out of battery as much as an inch.

 

 

Edited by mpmo
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I think the bolt hit the rim and for whatever reason that ignited the round. The powder would not all burn with it being open like that. Probably a once in 100 million chance of that happening. 

 

If you discover a different reason please share it. 

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Could it be you had a ejection failure from the prior round and the case was in front of the round in the mag?  If the bolt then came forward The bolt face might have had enough force to ignite the round in the mag.

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I had this happen on one of my Sportsmans Team Challenge rifles.  It happened twice in one match.  It was a new aftermarket bolt.

 

Finally narrowed it down to where the underside bolt and breechface come together was a touch sharp.  If the round being fed in didnt rise up enough the bolt caught the very top of the case, made it nosedive, and then lit off the primer.

 

I rolled off the edges on the breechface and cleaned the gunk from the mags so they feed better/smoother/faster.

 

No problems since.

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I have a new partial theory.

The case that was exploded in the magazine was not fired.  It was blown open by the other round firing.  A couple things point to this:

1.The un-exploded gun powder found all over.

2.The inside of the exploded case was clean and it does not appear to have a primer detonation.

3.The round that was stuck in half way to the chamber.  I believe the energy of the explosion sent the original round out of the barrel and this round that was sticking out was the one from the exploded round in the magazine.  It had enough energy that it hit the feed ramp and lodged itself halfway into the chamber.

 

I'm guessing I had an out of battery detonation that set the whole series off.  Only my second time using that ammo.  My gun might not like feeding it.  I did have a few other feed issues during the match.  My standard is CCI Mini-mag target and HP.

 

 

Edited by mpmo
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17 hours ago, Tom Freeman said:

Look inside that case and see if the priming compound is intact.

 

On mine, it was not meaning it lit off at some point.

 

Sorry, I was trying to get that across.  The priming compound is intact.

 

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