.22 cases rupturing - CCI Blazer

Avro125

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I'm not sure if it's the gun or the ammo. I'm leaning toward ammunition, but I'd like a few other opinions.

The ammo is CCI Blazer - the supposedly 'good' stuff that's sold in the 50-round boxes, not the bulk packs. The rifle is a Cooey Model 39. The gun is relatively new to me, and I've only put about 200 through it so far.

I recently noticed that the gun occasionally 'vents' some gas back at me: I can feel it fit my wrist and cheek. It seems to occur with one out of every 5 or 10 shots, but only when firing the Blazer ammo. I haven't noticed any issues with other ammo (mostly M-22) that I've fired. I looked at a handful of spent cases and it's pretty clear which ones caused the problem. The cases appear to have split open along the rim, and I suspect that some gas escapes and flows backward along the bolt channel and out at the shooter.

This is the ammo:


Here, you can see the scorch marks on the bolt face near the firing pin. It also looks like some gas gets channelled out of the extractor slot.




If you look closely (hopefully you can see it in the photos) you can see the split in the rim. The two in the front are the suspect ones. The three in the back are fine, and didn't 'vent'.





So, the question remains: is this an ammo problem or is it the gun?

I really like the gun, and I bought the ammo (Canadian Tire, last year) thinking that it was decent stuff.

Any help is appreciated. Thanks!
 
I'm not an expert by any means, but it sure looks like that brass is getting hit HARD.

Ok on second inspection... Headspacing issue?
 
I'm not an expert by any means, but it sure looks like that brass is getting hit HARD.

Ok on second inspection... Headspacing issue?
+1 on that. Looks like a very hard hit on the rim that seems to deform it. I do believe the CCI "Primimg" is the same weather or not its a 50, 500 or 550 round pack, all the same cartridge. The flat bottom almost looks bulged. I would be looking into a smith to check the headspace. If it's not head spacing see if you can adjust the firing pin exposure like on the mosins and back off the pin a bit.
 
Thanks for the replies.

Here are some pictures of the chamber:





Hasn't been cleaned yet, and it's not really green: that's just the white balance thrown off by the LED light.

Anyway, it looks - to my eyes at least - okay. There's a slight burr at the 12 o'clock position, and it's just big enough that I can feel it with a dental pick. It's not quite 1mm from left to right. The firing pin on this gun strikes at more or less the 9 o'clock position on this gun. I don't see any damage from the pin on the gun.

The brass is certainly getting hit hard - the tooling marks from the firing pin are being transferred onto the brass. And while I've tried different ammo in the Cooey, I don't think I've fired the Blazer in anything else. My other .22 is a 10/22, and it uses the flat bar type firing pin, not the circle that the Cooey has. I don't know if that makes any difference.

If it stops raining I'll try the Blazer out in the 10/22 and have a look at the spent brass.
 
Looking at that fired brass, it looks like the ones that ruptured had some space to expand back into. The others look fine. Looks like there may be some play or it's not going fully into battery. I don't know that I'm using the right terminology, but hopefully you get my drift.
 
My first thought was that the bolt is not fully closing. Probably it's the chamber, and it might just be that the chamber is dirty. I've had the same happen while firing some old cheap waxy ammo (NOT Blazer) in a Ruger MKII handgun and in that case it was wax buildup.

And that is one hail of a firing pin strike you've got going there. The impression is that it's actually bending the cartridges. Give a thought to the fact that it might be damaging the brass and causing it to leak hot gas.
 
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Well, went to the range and put almost a whole box of Blazer through the gun, along with some Win M-22 and some Remington stuff I had. I also fired a sampling of the same ammo through the 10/22. And...

wait for it...

I couldn't replicate the problem. I put over 75 rounds through the Cooey alone, and everything was fine. I noticed that the pin seemed to hit the Blazer brass a little deeper than the Win or Rem stuff, but other than that, no issues.

The only other thing that I discovered was that the lot number on the 'suspect' box (I only had a few cartridges left) was different than that of the 'fresh' box I brought out today. I have several boxes of Blazer, all purchased from two different CTC stores last year, but I can't find any more of the suspect stuff on my shelf. I Googled the lot number ( F22S52 ) but couldn't find anything.

Maybe it was just a few weak cartridges? Or maybe the gun is just dirty. I noticed that the extractor doesn't always want to pull the spent case out. I'll give it a good cleaning and go from there.

Thanks for everyone's help. If the problem comes back, I'll update the thread.
 
Well, went to the range and put almost a whole box of Blazer through the gun, along with some Win M-22 and some Remington stuff I had. I also fired a sampling of the same ammo through the 10/22. And...

wait for it...

I couldn't replicate the problem. I put over 75 rounds through the Cooey alone, and everything was fine. I noticed that the pin seemed to hit the Blazer brass a little deeper than the Win or Rem stuff, but other than that, no issues.

The only other thing that I discovered was that the lot number on the 'suspect' box (I only had a few cartridges left) was different than that of the 'fresh' box I brought out today. I have several boxes of Blazer, all purchased from two different CTC stores last year, but I can't find any more of the suspect stuff on my shelf. I Googled the lot number ( F22S52 ) but couldn't find anything.

Maybe it was just a few weak cartridges? Or maybe the gun is just dirty. I noticed that the extractor doesn't always want to pull the spent case out. I'll give it a good cleaning and go from there.

Thanks for everyone's help. If the problem comes back, I'll update the thread.

That's pretty symptomatic right there. But if there WAS an overloaded lot of Blazer issued it could go unreported because almost no one buying it is shooting it right now, it goes in the horde.
 
My eyes are not better than anyone else's, but I can see what looks like hammering by the firing pin at the 9 o'clock position. I can clearly see an outline of the round firing pin. Probably made when dry fired. Seems as if firing pin is too far out, especially on your spent shells, too much impression. If you could take firing pin out and inspect where the hammer hits and see if its flattened it out any. Good luck
 
Thanks for the replies.

Here are some pictures of the chamber:






Hasn't been cleaned yet, and it's not really green: that's just the white balance thrown off by the LED light.

Anyway, it looks - to my eyes at least - okay. There's a slight burr at the 12 o'clock position, and it's just big enough that I can feel it with a dental pick. It's not quite 1mm from left to right. The firing pin on this gun strikes at more or less the 9 o'clock position on this gun. I don't see any damage from the pin on the gun.

The brass is certainly getting hit hard - the tooling marks from the firing pin are being transferred onto the brass. And while I've tried different ammo in the Cooey, I don't think I've fired the Blazer in anything else. My other .22 is a 10/22, and it uses the flat bar type firing pin, not the circle that the Cooey has. I don't know if that makes any difference.

If it stops raining I'll try the Blazer out in the 10/22 and have a look at the spent brass.
Is it just me or does that look like you are missing quite a bit of the barrel surrounding the chamber? That would certainly cause ruptures if you are.
 
Yea, nothing to support the cartridge rim.
Anyone with a 39A can you verify if the chamber mouth is supposed to look like that?
 
...and the verdict is: headspace issue.

That's pretty symptomatic right there. But if there WAS an overloaded lot of Blazer issued it could go unreported because almost no one buying it is shooting it right now, it goes in the horde.

Okay. This ^^ got me thinking. Maybe the issue hadn't been reported because no one is shooting any .22, they're just hoarding it. So, I called the number on the Blazer website, and spoke with an ammo tech. We exchanged a series of e-mails on the issue - I didn't have any of the 'suspect' ammo left and was told I couldn't / shouldn't mail spent cases across the border - so photos had to suffice.

The ammo tech asked for some measurements of the case rim, and in the process of tracking down the cases I'd set aside, I came across more. I took some better photos with my poor man's emergency tacti-cool macro lens, and sent them along with the measurements of the rim to the CCI rep.

Their conclusion is that it's a headspace issue. I was sent a document that pointed out where a secondary ring formed near the case rim, suggesting excessive headspace.

The gun was bought used, and I have no way to tell if the bolt is original or not. I also don't have any go-no-go gauges to check the gun. The gun is only worth about $100, so I'm not sure if it makes much sense to pay someone to inspect it for me. The only thing I can say is that with the bolt closed on an empty chamber, I can shove the bolt handle forward another .007". I don't know of this is normal on the Cooey 39s or not.

This still doesn't explain why it only seems to happen with one particular lot of the Blazer ammo, however it's entirely possible that the ammo is on one side of 'within spec' and the gun is at the other side of the spec, or even slightly out-of-spec. Add the two together and maybe you've got a problem. The CCI rep said that the ammo lot in question was produced in 2011, consisted of 135,000 rounds, tested well and they've received no reports of failures or other problems. Further, I'd imagine that much of the .22 ammo shot nowadays is in semi-autos, where venting from a case split like the ones shown below would be contained within the receiver, and likely go unnoticed by the shooter.

I have to say that I was really impressed with the service from CCI. Their ammo tech spent some time working with me to resolve (or at least identify) the issue. All over a $3.99 box of .22. Well done.

Here's the higher-res pictures. If you ever need a super-close-up photo, just turn a pair of binoculars around and shoot through the objective lens and out the eye piece. Turns the binos into an improvised microscope of sorts. Works pretty well in a pinch.

In some of the photos, you'll see the secondary 'ring' formed just above the rim of the case.


Case split #1


Case split #2


You can see a couple of gouges on the rim, indicating two or three tries with the bolt to extract the stuck case.


Firing pin strike #1


Firing pin strike #2
 
2 of the 3 Cooey's I've owned (two model 60's and one 39) have had this issue with certain lots of ammo. All where old, worn, rifles so not sure if it's a manufacturing fault or just worn out guns. Maybe it's a common problem once a Cooey starts to get worn out?
 
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