High Pressure? (with pics)

[F. Guffey]

i bought this lot of cases brand new. Lot of 50. They have never been cleaned. I opened the box, ran them all through my redding FL resisizing die, trimmed, uniformed primer pockets, charged with about 3 week old powder, and seated my bullet without a crimp.

I understood your answer; I have had more than 100 cases split through the case body, I have never had a case split through the case body that did not show gas leaking through the split and between the chamber and case body. I have never has a chamber that caused splits as thought they were hit with a shaped charge in the case body; again, I said the cases were split.

I formed thousands of cases for the 8mm57 chamber, after I started forming cases I never had another split case. I used the same powder and the same bullet, forming cases allowed me to get rid of the corrosive primer and when forming 8MM57 cases from 30/06 cases I controlled the clearance between the case shoulder and chamber shoulder.

I still have all of the 8MM57 cases I pulled down for the powder and bullets, I honestly do not believe the manufacturer of those casers was concerned about a user complaining about the lousy millage they were getting from what was left of the case after firing. Again, I reduced the powder charge, 3.100 fps seemed fast for a 8MM57.

I do not believe in magic but if you say there was no evidence of hot high pressure metal cutting gas escaping through the split into the case or out of the case I have to consider magic.

F. Guffey

 

[Stats Shooter]

I have not had a lenghtwise crack in a case like you show in your picture.

What I HAVE had is a casehead nearly separate on the 2nd firing of some .308 brass. A big crack formed near the web going half way around the case. This happened in a gun with thousands of rounds down the barrel, and in a fairly mild load of IMR 4064. Again, the brass was only once fired, and prepped the same way as I prep all my target .308 loads.
The powder was a new lot, the primers were new, and there was NO crimp.

This only happened to one case, but there were no warning signs as to its impending cracking. I dismissed it as bad brass.

BUT.

I do not believe in magic but if you say there was no evidence of hot high pressure metal cutting gas escaping through the split into the case or out of the case I have to consider magic.

It is a chrome lined chamber, but there was a discoloration ring right where the crack occurred indicating gas being blasted against the chamber wall. It didn't cut a groove, but it was obvious where the crack happened.

Also, I had smoke/gas leaking back towards me and I was shooting over the chroney at the time and it registered 600 fps below average.

Finally, I am not a fan of Hornady brass. Their bullets are great, their factory ammo is fine, their reloading products are fine from what I hear....but I have had bad luck with their brass being too soft. So soft that loads in my .338 Lapua and .300 win mag got stuck in the chamber at charge weights (and velocities) well below max. I then try another brand of brass, any brand including the "flimsy" federal brass, and have no issue with velocities well in excess of the velocities that stuck the hornady cases.

And when I say stuck, I mean needing to pound them out with a brass rod and a hammer.

So, I avoid Hornady brass.

 

[insco3]

F. Guffey,

I guess this is where I was differing to the forums expertise. The photo that shows the crack does indeed show gas leakage towards the head stamp of the case. My thoughts are if the brass didn't expand fast enough to seal, all the pressure is relieved through the path of least resistance (through the bore and out the crack). I think you want to see a dirty head stamp from the escaping gasses. What you see is what you get. I may have thumbed it clean to inspect better, but no tumbling or anything of that nature was used.

I assure you my magic profession was replaced with a real job many moons ago



I think a bore scope will reveal any visual abnormalities with the chamber?
If visual passes, Firing factory brass with success should move me on to attempting hand loads with a new brass manufacturer.

your thoughts?



Thanks again for all of the forums help.

Insco3

 

[cdoc42]

I think Unclenick's reference to the use of the bore scope was to inspect the inside of the cases, not the rifle bore. Use of the "dental pic/bent paper clip tip" will be more meaningful if you find a suspected case, then hacksaw it in half to really inspect it.

I join with those opining brass case defect; after 42 years of reloading I can say I have never had a case crack like the one in your photo. All have been web and/or neck cracks due to case failure caused by repetitive reloading.

 

[Unclenick]

Yes, I'd meant to suggest you use the scope to inspect the brass. However, if that crack appears in the same orientation every time you eject a case with one, please do look at the chamber as well.

 

[Mike Irwin]

"i bought this lot of cases brand new. Lot of 50. They have never been cleaned. I opened the box, ran them all through my redding FL resisizing die, trimmed, uniformed primer pockets, charged with about 3 week old powder, and seated my bullet without a crimp."

Exactly. I've had numerous similar mid-body splits with BOTH brand spanking new AND brass that has been fired and reloaded many times.

The cause is a weak point in the brass that fails.

Cartridge brass isn't perfect. The manufacturing process isn't perfect. The reloading process isn't perfect.

Yes, there is evidence of gas leaking out of the crack and into the chamber because that's exactly what happened.

The high-pressure gas pushing out of the cracked area overcomes the resistance of the brass being pushed against the chamber walls.

My guess, though, is that it doesn't happen at the start of the ignition cycle, when chamber pressure is rising, but AFTER peak pressure, when the brass begins to contract away from the chamber walls.

 

[insco3]

Thanks Mike Irwin

Makes sense to me.

This would explain why the cases are cleaner than F. Guffey would like to see.


Insco3

 

[F. Guffey]

This would explain why the cases are cleaner than F. Guffey would like to see.

Again, I do not want anything between my chamber and case but air, I do not want a lot of air, that is the reason I size my cases to fit the chamber. And then there is clean air, the air I have between the chamber and case must be clean because the case is embeddable. And then there is time, I understand slow burning powder is cute but there is a limit, if the powder burns too slow there is a chance the case neck will not seal the chamber; when the neck does not seal hot high pressure can leak back and past the neck and then get trapped between the case neck and case head. I understand that does not present a problem for anyone else but it does for me when the pressure drops inside the case.

I have absolutely no interest in firing cases that split the case body, I have loaded rounds that will split the case body 4 out of 10 rounds, everyone of the splits will blacken the case body and chamber. I can prevent the splits by busting up the clods and changing the cases and primers. I could pull the bullets, bust the clods and then reseat the bullet but, again, I would still have Berdan Primers.

Any how; anything between the case and chamber when fired will be embedded into the case and again I am the fan of having nothing between the case and chamber but clean air.

F. Guffey

 

[F. Guffey]

The cause is a weak point in the brass that fails.

A snith that was set up at the Market Hall gun show had one of his customers accuse him of building a custom rifle that had all kinds of head space problems, the smith told him to bring it to his shop, and then he examined the case.

I did not get involved, I waited until they had finished and the man with the defuk rifle made a it to me. I asked him to show me the case from the rifle with 'bad head space'; he did. I examined the case and asked the proud owner if that was the only case he had for this wildcat chamber? I asked him is he was shooting and reloading that one case over and over and over and over? I told him that case was so thing it would have trouble standing up straight without support. The builder/smith came down to examine the case again and then suggested the case be examined by a third party. The rifle owner was instructed not to tell the third party examiner what I said and he was told not to tell the third party who build the rifle.

Off he went to a smith of few words: The smith took the case, ripped it apart and measure the thickness of the case body; the thickness of the case was .002", the smith informed the proud owner .002" is a good thickness for paper but not for a case that has to be sized and ejected after firing.

To split a case body there has to be something else going on besides a defect. I could not believe the reloader loaded those cases so may times the case was so thin it would not stand up straight. I offered to form 200 cases for free from new/never fired cases and I promised him I would form the cases with .002" clearance but when he left he was not speaking to me and he did not return to the gun shop with the rifle.

F. Guffey