incipient case head seperation

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incipient case head seperation

Post by marksman » 11 Jan 2020, 10:35 pm

this can really ruin your day :thumbsdown:

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Re: incipient case head seperation

Post by Member-Deleted » 11 Jan 2020, 10:52 pm

Yes that would be a bugga especially if it was the first shot on a weekend out .and I like that stock mate
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Re: incipient case head seperation

Post by bladeracer » 12 Jan 2020, 12:12 am

Nothing incipient about that!
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Re: incipient case head seperation

Post by wanneroo » 12 Jan 2020, 1:02 am

Any thoughts on what went wrong?

I do the paper clip test on my rifle brass and will find brass that has case separation signs from the inside but not from the outside.
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Re: incipient case head seperation

Post by JimTom » 12 Jan 2020, 7:10 am

bladeracer wrote:Nothing incipient about that!


+1

Mate how old / how many reloads has that brass had? Is this a load that you have used previously? Which one do you suspect is causing the issue?
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Re: incipient case head seperation

Post by Blr243 » 12 Jan 2020, 9:01 am

I always thought that situation arose from non thorough case inspections and many sizing operations ....this post prompted me to google case head separation causes. The first info I found suggested the problem happens when cases a sized a few though too much .... it’s easy to see how some people , in the interest of reliable function in the field, might size their cases a bit too much ..... so this post I think is a good reminder to us all to maintain safe procedure , care and precision..... esp for myself at the moment about to embark on a fair bit of 303 reloading where my military chamber could be a bit sloppy
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Re: incipient case head seperation

Post by SCJ429 » 12 Jan 2020, 9:35 am

Pushing the shoulder back when sizing and the case growing forward to fill the chamber when firing is the main cause. Fairly easy to detect while reloading if you are looking for it.

http://blog.westernpowders.com/2015/07/ ... and-cures/
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Re: incipient case head seperation

Post by Blr243 » 12 Jan 2020, 11:06 am

I once got advice from an employee at a gun store to full length resize every time ....if I have dies and I adjust them carefully to give my ammunition I nice snug fit , surely that’s got to be smarter than taking my brass back to factory spec every time and then blasting it to fit my chamber again ... I was surprised to hear that advice from a gun store
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Re: incipient case head seperation

Post by straightshooter » 12 Jan 2020, 11:19 am

I would be more confident in my comments if the pictures were more detailed and clearer and included additional views.
The failure looks to be in a peculiar position as it appears to be at the juncture of the belt and the case body. Normally this would either be solid or quite thick depending on manufacturer.
If the failure was due to repeated full length resizing or even just neck sizing using a FLS die then the failure would be expected to be in a thinner portion of the case somewhere forward of the solid belt.
You might need to sacrifice one case from that maker to see what gives by cutting it lengthways and noting the brass thickness in the web areas around the belt.
You should then be in a position to assess the potential for future problems.
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Re: incipient case head seperation

Post by marksman » 12 Jan 2020, 1:02 pm

the case is a 3rd firing and only neck sized, l'm not 100% sure why it happened :unknown:
what l think happened is that the case was very undersized from factory with thin material in the wall that thinned out more in this area as the case grew to the shape of my chamber, l have seen this happen on first fire for 303 with thin walled cases
l will be scrapping this lot of cases anyway, l suppose l was lucky not to have been on a hunt

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Re: incipient case head seperation

Post by GQshayne » 12 Jan 2020, 5:29 pm

Blr243 wrote:I once got advice from an employee at a gun store to full length resize every time ....if I have dies and I adjust them carefully to give my ammunition I nice snug fit , surely that’s got to be smarter than taking my brass back to factory spec every time and then blasting it to fit my chamber again ... I was surprised to hear that advice from a gun store


I have full length resized my .243 pig loads for over 30 years, and I have cases from my first ever loads done in the 1980's (PMC). Some of them would have been reloaded many times. I do not record such info, just watch for signs of them getting tired. Neck sizing will give better accuracy, and you would think the brass would last longer. But for rounds that I want loaded fast, and as slick as possible, like when you are firing multiple shots quickly, I go full length. So I think it depends on your application, not just accuracy and case life.
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Re: incipient case head seperation

Post by straightshooter » 14 Jan 2020, 6:25 am

Thanks to your additional picture it is apparent now that the separation is some distance ahead of the belt.
It now looks to me that you have a combination of issues.
With most belted magnums it is possible to headspace on the shoulder or the belt or both. In your case you have what looks like a 375 that is designed with considerable body taper and a very small and gentle shoulder angle by today's standards and if the tolerance on the belt is substantial then on ignition the case will be driven forward as far as the belt will permit with little or no support from the shoulder. So it is very important that the headspacing on the belt is close to minimum tolerance if you would like to enjoy decent case life.
It would also be sensible to investigate whether your neck sizing process is not modifying the shoulder or body taper in any way.
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Re: incipient case head seperation

Post by SCJ429 » 14 Jan 2020, 8:40 am

In the first photograph there is a dent in the shoulder area which looks like a excess lube dent when you are sizing. What caused that dent?
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Re: incipient case head seperation

Post by marksman » 14 Jan 2020, 10:12 am

SCJ429 wrote:In the first photograph there is a dent in the shoulder area which looks like a excess lube dent when you are sizing. What caused that dent?


l saw that myself and wondered :unknown:
l had to jam a 45 cal brush into the case tight and give the rod a real hard pull to remove the case
that may have been the cause hitting something on the way out :unknown:

l hear what you are saying straightshooter :thumbsup:
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Re: incipient case head seperation

Post by straightshooter » 15 Jan 2020, 7:20 am

If you are interested you can do a crude but practical headspace test in a couple of different ways. Note this only works with rimmed or belted cases.
1. Place a short piece of 1mm solder wire under the case head while held in place under the extractor and then chamber the assembly. Your BRNO should have enough cam forward leverage to allow you to fully close the bolt. Now carefully measure the thickness of the flattened solder. Note it can be easily damaged in the process.
2. Cut discs from aluminium soft drink cans that will neatly fit in the bolt face. You will need to remove the firing assembly. They will be close to 0.004" thick. The bolt will probably close over one but if it closes over two or more then that is an indication of the extent of your problem.
If one or other of these tests fails to reveal a headspace issue then your problem is due to excessive sizing.
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Re: incipient case head seperation

Post by Varmtr » 22 Feb 2020, 11:30 pm

Get some headspace gauges to check. I try to set up headspace as close as can get to 0.000" on bolt actions.
From what I can see I think yours a belted case if so headspace is from the bolt face to the edge of the belt ( neck side ). If it is out of headspace it may need the chamber re cut which also involve facing back the tenon one thread to time the barrel ( if it has open sights etc etc ) and recut the chamber also recut the barrel shoulder.
How are you neck sizing your cases.
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