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  #21  
Old 03-20-2020, 01:26 AM
TinMan TinMan is offline
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Be sure to include the lot number from the box or end flap.
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  #22  
Old 03-20-2020, 02:02 AM
17tbs 17tbs is offline
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Quote:
Originally Posted by Bill K View Post
If that damage to the bolt face was done by the failed rim, it also looks like this bolt face could have had a issue with soft metal too begin with. Sure looks like more was involved than just a failed rim/cartridge.
Could be wrong. BIll K
Bill,

That is a stock photo of the CZ 452/453 system bolt. This isn't the actual weapon that had the case head failure.
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  #23  
Old 03-20-2020, 02:05 AM
17tbs 17tbs is offline
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Quote:
Originally Posted by TinMan View Post
As I recall, some of the early failures involved with semi-autos in 17HMR stemmed from very dirty chambers, which made the rounds fire slightly out of battery. Maybe a bit of headspace issues also.
I concur, based on the case neck to shoulder profile not being sharp at the shoulder and body juncture. This would actually indicate that the weapon fires without the bolt fully locked and down which possibly would cause what we see here.
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  #24  
Old 03-20-2020, 02:06 AM
Bill K Bill K is offline
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The bolt face of my CZ hmr sure does not look that messed up. Is it the angle of the bolt face taken on the photo or light/glare on the face that makes it look so uneven? Bill K
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  #25  
Old 03-21-2020, 01:28 PM
Rbertalotto Rbertalotto is offline
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A few things...

This was the first time my Grandson used this rifle and only the third or fourth time he has used any magazine, bolt action rifle.....feeding from the magazine. Up to now we have been single feeding and/or a single shot rifle.

So....The cartridge before this one did not fire, it ejected with the bullet in the case. No movement.....The next round was this one.

Could it be the gun fired these two times a bit out of battery. The first cartridge didn't fire because the firing pin didn't reach the rim properly?

The second blew because the bolt wasn't totally closed. That would explain a split case AND a blown rim.

It is possible, he being a new bolt action shooter, he wasn't handling the bolt with enough force.

I'm going to do some testing when I get a chance to see if this gun will fire a bit out of battery

Stay tuned!
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  #26  
Old 03-21-2020, 03:00 PM
GLWenzl GLWenzl is offline
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I agree with and like your analogy. Although it seems like a bolt gun should never be able to fire out of battery.

The reason I agree with what you are saying (and going to do) is that I have tried to simulate some of my theories of semi auto 17s in a bolt gun. For example, on the cases I have done the push test on (all of them) but have failed, I have fired in a bolt action to replicate a semi-auto blow back design picking up that round from the magazine and forcing the bullet back into the case resting on top of the powder and creating and hopefully showing high pressure signs. There are many variables to this that I might not be able to replicate, one is when the Eley ammo has a bullet set back, it will rest on top of the powder column but still slightly making contact with the neck. This condition I was at first thinking would be the most severe pressure (maybe is?) but as of today all of them have fired and shot normally with with the same POI. All other types of ammo that I have and tested will leak out powder once the bullet is set back I to the case.
None of this means anything except I am curious and want to learn more about making the semi auto work like like it does in the A17 which I had high hopes that we would have seen an A17 HM2 by now.

Sorry, I get rattling on like that. Hope you can find the cause and am very happy the experience wasnít any worse that it was.
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  #27  
Old 03-21-2020, 03:04 PM
GLWenzl GLWenzl is offline
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I should also add that as of today I have never noticed any issues due to a cracked case and powder deterioration. Every single case I have tested with a cracked neck in both HMR and HM2 have all shot extremely well, way better than it should. I did not say it couldnít happen like others have mentioned in this thread. Iím only stating what I have experience as of today.
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  #28  
Old 03-21-2020, 03:05 PM
Double D Double D is offline
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Quote:
Originally Posted by 17tbs View Post
I concur, based on the case neck to shoulder profile not being sharp at the shoulder and body juncture. This would actually indicate that the weapon fires without the bolt fully locked and down which possibly would cause what we see here.
Nope. Not very likely at all. Fired unlocked would have left a circular mark around the case in front of the rim from the back chamber.


Quote:
Originally Posted by Rbertalotto View Post
A few things...

So....The cartridge before this one did not fire, it ejected with the bullet in the case. No movement.....The next round was this one.
A very big indicator and probably the best piece of evidence in this whole incident.

Quote:
Could it be the gun fired these two times a bit out of battery. The first cartridge didn't fire because the firing pin didn't reach the rim properly?

The second blew because the bolt wasn't totally closed. That would explain a split case AND a blown rim

It is possible, he being a new bolt action shooter, he wasn't handling the bolt with enough force.

I'm going to do some testing when I get a chance to see if this gun will fire a bit out of battery

Stay tuned!

Again not very likely. If you can get the gun to fire out of battery the back of the case should bulge around around the head in front of the rim, as the case will be forced backwards out of the chamber when it fires, and the head will be unsupported.

If you can get that gun to fire unlocked send it back to the manufacture for repairs. I don't know how the sear and striker connect in this gun, but if this fires unlock, there is a problem with this part of the gun. If this gun did fire our battery the damage would be different.
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  #29  
Old 03-21-2020, 05:48 PM
Rbertalotto Rbertalotto is offline
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Quote:
Fired unlocked would have left a circular mark around the case in front of the rim from the back chamber.
Good point! Agree...

This gun has CZ's set trigger system.....Push trigger forward to set, then a couple ounces to fire. Not sure this has anything to do with anything...

I'll test the theory...
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  #30  
Old 03-21-2020, 10:31 PM
Daryl Daryl is offline
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Never had a rim failure, but a few split necks, yes.
Have noticed that the WW brand headspace varies some. This is only noticeable in my Martini with very snug headspace on Hornady ammo when I built the gun.
Never had a CCI or Hornady case display ANY headspace tightness.

The tight WW cases (not had one go off when chambering - that might be exciting) strike 3/8" to 1/2" to the right of the normal grouping, but also into a small group, when firing on targets.

I know, when chambering them, if to hold centre or to the left. Bit of a pain, but not insurmountable.
There is no change in the Marlin, firing the same ammo.
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