Brass perforating at the neck?

D

Dennis Sorensen

Guest
Here are two pictures of .300 Weatherby brass fired about 5 times. The brass had 3 small perforations developing in the neck. They look like gas cuts from inside the case.

The first picture is of one case sectioned down the middle... with red arrows showing about where the gas cut is... hard to see on the outside with the light the way it is...
300%20necks%20outside.jpg


This second picture is of the same brass taken from the inside against a light background... you can see the holes...
300%20necks%20inside.jpg


I think the brass had very small flaws from the factory forming the brass and with a few firing this is showing up and leaking gas. It has marked the shoulder of the chamber. You can see a small mark on a new brass when it is chambered... it may only be debris but I am going to set the barrel back a few thou and clean it up with a reamer.

Anybody have another theory on this...? why the brass failed? I am certain it is an inside out failure, not a fault of the chamber.

.
 
Dennis,

I can recall similar failures with the domestic military brass years ago. We did notice that occasionally a round would come along with the tiniest hint of a fold there & surmised that was the stuff that gave up later.

John
 
I've never seen perforations like this in the necks of cases, but have seen new or nearly new case necks with flaws in them from manufacture I think. At first they just look like tiny dents or scrapes in the necks, but on firing they develop into holes.

Were these cases any thinner where they developed the holes than elsewhere on that part of the neck? Very strange, but then I don't shoot any Weatherby cases. I do use fairly, uh, stiff loads in most of my rifles though, and haven't seen it with them.
 
Dennis, that small mark in the shoulder area looks exactly like a kernel of powder. Had it happen to me and the kernal didn't crush to my surprise, bolt didn't "cam in" all the way, but I tried.
 
PEI Rob said:
Dennis, that small mark in the shoulder area looks exactly like a kernel of powder. Had it happen to me and the kernal didn't crush to my surprise, bolt didn't "cam in" all the way, but I tried.
Click to expand...

It's tough to take a picture of the brass but the "perforation" appears like a little burnt crack... it wasn't a kernel of powder... bolt closed and opened normally...

I'm going with the flaw in the brass that is just appearing with repeated firings...
 
Looks like fatigue to me. How many times has it been fired/sized and has it always been fired in the same chamber? May just be bad brass. I think the Weatherby brass is made by Norma. I've seen Norma brass give up sooner than I thought it should in other guns myself. I'm not putting down the Norma stuff, just giving my experience with it.--Mike Ezell
 
Lynn said:
Dennis
If you've ever done alot of wildcatting you'll notice as you expand necks that some brass has inclusions or seperation lines through it.The classic split necks usually run in a perfectly straight line.
In your photos the pin holes appear to be at the same exact point on the brass.Since new brass shows the sign of getting nicked before firing if I read your post correctly? I would think a burr is sticking up in the chamber.
Lynn
Click to expand...

I could not find any burr in the chamber and close inspection of the brass shows the hole is bigger on the inside...

After the owner noticed the cracks in the brass, he took a new case and marked it with a felt pen and closed the bolt on it... and thought it marked the case... I think it was debris left from other cases leaking gas that marked the case...

I cleaned the chamber up with a reamer to be sure and the headspace is correct and he is starting out with some new brass...
 
Dennis
I recon when I finally get to see an elephant fly I will have seen about everything because until now I had never seen this before.
I have seen dents in the shoulder of the brass from powder kernels spilling into the chamber when a round was pulled apart on extraction. But never a hole from the inside out.
Ted
 
As they have only been loaded five times . I would go for small foriegn inclusions in the brass when it was drawn into strip.
That dissapear and close up during case formation and drawing.
The thinnest most worked part of the brass is the most likely place to open up first from this kind of fault.
If they were much older more work hardened cases that have been exposed to a lot of Ammonia from excessive bore solvents in the chamber area or in liquid case cleaning I would say stress corrosion leaching out the zinc from the copper.
 
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Dennis,

I was talking to a couple of guys today & one reminded me that what you have there is very like how old Aussie .303 brass used to fail at the neck/shoulder junction when it got a few years on it & maybe became a tad brittle or some other metallurgic transformation occurred. We're talking about WWII vintage brass that used to be reloaded by a local company in the seventies or thereabouts.

Any chance that the brass involved has been around for a while (maybe even before the shooter took possessition of it)?

John
 
J. Valentine said it well...

This is along my line of thinking...

I would go for small inclusions in the brass when it was drawn at the manufacturing level that disappear and close up during case formation and drawing. The thinnest most worked part of the brass is the most likely place to open up first from this kind of fault.
 
I had seen what appeared to be the same on some Remington 7mm Mag brass about 10 or so years ago. I just threw away the brass and went on. Several of the pieces in that lot did it and it seemed to appear around the 4-7th firing. I have also seen this on a few pieces of Norma 6ppc brass for a sako around 12 years ago. Never looked enough to tell if it was from the inside out. I actually just figured it was from stress of resizing with an expander ball even though it was on the shoulder. I haven't seen it since then. Interesting...

Hovis
 
Dennis, I meant the spot higher up on the left. No idea what your hole was caused by but have seen it before, assumed an inclusion in the brass. Maybe its just the light from the camera that I circled in red.

Cheers

kernel_dent.jpg
 
John Kielly said:
Dennis,

I was talking to a couple of guys today & one reminded me that what you have there is very like how old Aussie .303 brass used to fail at the neck/shoulder junction when it got a few years on it & maybe became a tad brittle or some other metallurgic transformation occurred. We're talking about WWII vintage brass that used to be reloaded by a local company in the seventies or thereabouts.

Any chance that the brass involved has been around for a while (maybe even before the shooter took possessition of it)?

John
Click to expand...
John that old 303 brass was made brittle by age hardening from long storage and firing with mercury primers . Also the brass was not well made and was work hardened and dirty before it was ever loaded possibly due to the need for mass production at the time .
I have seen them split right down the side of the neck after first firing.
Large military chambers dont help either.
 
One thing I am concerned about with the Weatherby chamber is that because the shoulder angle is a radius so the junction of the neck and the top of the shoulder can be a very sharp edge on some reamers that really over stresses the brass and leaves a sharp crease in the brass. It should be more rounded and smooth not a sharp crease.
This could be contributing to the problem.
I am only speculating on this point as food for thought. I may be all wrong on this point .
The first photos don't look quite right for a Weatherby shoulder . I think a rechamber is a good idea.
 
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No external dents... that is just the lighting...

Here is one picture of the inside... not cleaned or touched...

inside%20300.jpg
 
Interesting marks on the inside of the neck , that are similar in size and length to the ruptured section and have the same orientation and also some with an angled orientation . Could these marks also be faults within the brass?
It's the angled marks that intrigue me.
 
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I have seen these marks on 300 WBY brass in the past that had never been fired. Brand new out of the bag, had holes in the shoulders. I am going to say this is not all that rare in the production process.

I have lots of 300 WSM cases that are split. In fact, my favorite set of match brass looks pretty ugly, and I can pretty much guarantee that nobody else would shoot such cases. 4 of the 10 are split like this.

They still shoot ok.

Dbrass.jpg
 
The thing with using cases in this condition is that the gas escaping is going to cut up the neck area of the chamber.
 
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