Back end of casing blew off

[RGBellCSI]

I was plinking with my 15-22 today and had an interesting experience. I shot one full mag of CCI standard velocity with no problems. On the third to the last round in the 2nd magazine, the back of the casing blew off. Smoke came out all around the receiver. When I removed the magazine, the back of the spent casing dropped out. (see attached photo). The casing was sitting part way into the chamber. I was able to remove it with my fingers. There was no evidence of a squib but I decided to stop shooting the gun until I could get it home and fully inspect it.

After disassembly, the barrel was clear and I didn't see any damage.

 

[merl67]

Wow first time I've ever seen a 22lr do that. I've seen rifle brass that was reloaded one too many time do it. The only two things that come to mind are an out of battery discharge, or faulty ammo.

 

[Bob L]

Where is the notch in the case head in relation to the extractor? Is it possible that when the bolt went forward, the extractor hit the rim of the case and broke the chunk of the rim out (defective case). Then the case still fired because of the compound under the rim stayed in place? Just trying to figure out what happened.

 

[LoboGunLeather]

This is commonly called a case head separation. Most likely cause is an area of the cartridge case that was weakened for some reason (being .22 rimfire I would assume a manufacturing fault of some kind), but it could also indicate a chamber that does not fully support the cartridge case when fired.

Not a common occurrence but not highly unusual either. I would be looking carefully at fired cases to see if there are signs of unsupported areas of the chamber. If not, I would take this incident as a case failure with that particular lot of ammo in that particular rifle.

 

[Injunbro]

I'd try a case in the barrel to see if they're truly seating completely. It's possible the gun is firing w/ the bolt not completely closed... either a short or fouled chamber.

 

[CH4]

Looks like a case head separation from firing out of battery. If everything was working fine before, and as others have said, you may want to clean your gun. Not uncommon

 

[RGBellCSI]

Update

I clean my guns after each use with CLP, a bore brush and a bore snake. The chamber and barrel were clean.

The rounds appear to be seating properly in the chamber. I don't think it was out of battery.

The piece missing from the head is 90 degrees from the firing pin mark, which is consistent with the geometry of the bolt. The extractor may have hit the rim and caused a defective round to break.

I used a brass catcher, so I was able to inspect the other spent casing and there were no defects.

I am going to go with a defective round. I will watch it closely the next time I take it to the range.

 

[DWalt]

I have seen similar case head separations, but perhaps not quite the same thing. Those I have seen were cracks going peripherally around the largest diameter of the rim, resulting in a thin disc separating from the case. I cannot say how many of those I have seen, but probably at least a half-dozen back in the days I was coaching a kid's rifle team. I always assumed it was a metallurgical-related failure. It never resulted in any gun damage or shooter injury.

 

[vipermd]

Wow first time I've ever seen a 22lr do that. I've seen rifle brass that was reloaded one too many time do it. The only two things that come to mind are an out of battery discharge, or faulty ammo.

WOW is right!! out of all the 22 lr rimfire I have shot, I had never seen that. Be Safe,

 

[s&wchad]

It’’s not common these days, but it does happen. That’s why modern .22 rimfire firearms have recessed chambers or bolt faces, which are designed to protect the shooters and bystanders from casehead failure. It sounds like your gun was in battery and did its job.

I’d chalk that up to a faulty cartridge. You may want to contact CCI. I suspect they’d like to examine the failed cartridge and the remainder of the box.