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First Indication of a PPU Case Head Separation

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Category: Reloading
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Printed Date: February 21 2024 at 12:48pm
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Topic: First Indication of a PPU Case Head Separation
Posted By: britrifles
Subject: First Indication of a PPU Case Head Separation
Date Posted: June 12 2022 at 8:15am
I have my first indication of an incipient case head separation in my first batch of PPU cases.

Unfortunately I have not logged the number of reloads, I suspect 30+, perhaps over 40.  Had to get the lighting just right for it to show in the photo below.   It does not look nearly this obvious in normal lighting. 

This was on the first firing after a partial length resize (I think I’ve P/L resized these cases three times now, typically get 10 to 15 neck sizing reloads between each P/L resize).  I shot this on Friday at the D-Day match.  I like to have the cases P/L sized for a major match, as it makes bolt cycling and lockup very fast for the rapid fire stage. 

I’ve been tracking the number of reloads in subsequent batches and now at 15 neck sizings and one partial length resize.  





Replies:
Posted By: Shamu
Date Posted: June 12 2022 at 12:13pm
Yep that's the classic symptom!



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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)


Posted By: britrifles
Date Posted: June 12 2022 at 1:39pm
That area of the case just forward of the head undergoes a lot of plastic strain, and thins the brass.  I can see it getting thin looking down the case mouth, the thin area will be in shadow if you shine a light down into the case.  Hate to junk this whole batch, but that’s probably what I should do. 






Posted By: Honkytonk
Date Posted: June 12 2022 at 1:54pm
Might just be a weak one in the batch but probably binning the rest of that batch is the way to go.


Posted By: Breaker
Date Posted: July 23 2022 at 9:00am
I wouldn't toss out the others from that batch, but downgrade them to low pressure cast round ball loads. they could last many more shots at that level of pressure. Thats just my practice when brass gets to this point and may not be for everyone. Those certainly lasted through many loadings already!


Posted By: A square 10
Date Posted: July 24 2022 at 7:24pm
breaker - welcome if ive not said it before , i think you are addressing reloaders that dont soot the low pressure loads you mention often  , i do and understand where your going with this , but unless that fits their shooting patterns it wont help them much , maybe they have friends that do they could give these to , it is a good way to salvage these for an extended life use , 


Posted By: britrifles
Date Posted: July 25 2022 at 7:06am
My typical approach is to cull the cases that show the white line as an impending case head separation.  The lot eventually gets down to less than 40 cases at which point I throw the remaining cases in the scrap container.   I try not to mix in new cases with old cases.  




Posted By: DaveNo5
Date Posted: July 25 2022 at 9:41am
If you're going to discard it, could you section it with a hacksaw to see the extent of the wall thinning?  I am curious as to what it looks like inside.  Dave

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DaveNo5


Posted By: Shamu
Date Posted: July 25 2022 at 11:42am
Here you go. I crushed the case mouths to prevent others fishing them out of the trash at the rage & tying their gun up.





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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)


Posted By: britrifles
Date Posted: July 25 2022 at 11:50am
Yup, done enough of these to be able to spot the “white line of death”.  Mine usually crack a bit lower than the photo Shamu posted, about 5/16 inches up from the bottom of the case head. 


Posted By: Dragunov
Date Posted: July 25 2022 at 11:58am
This is why I always keep a broken she!! extractor in the butt trap (just in case).


Posted By: Shamu
Date Posted: July 25 2022 at 2:09pm
I've had a couple go there. This odd positioning seems unique to the Remington nickle-plated I got a bunch of years back.


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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)


Posted By: A square 10
Date Posted: July 25 2022 at 9:18pm
wow , thanks for doing that it really brings home what is happening in there - photo/1000 words kinda thing 


Posted By: britrifles
Date Posted: July 26 2022 at 4:28am
Here’s what mine look like.  The progression of case web thinning (far right), and left to right, the “white line of death”, visible cracking and head separation. 

These happen to be Canadian DI Mk 7 cases, with 40+ reloads. 




Posted By: Dragunov
Date Posted: July 26 2022 at 5:12am
Britrifles, could you share your load with us? I use mostly PPU brass with IMR 4064 (39 grains) as my "go to" with both 180 JSPs and 174 FMJs. But, even neck sizing only, 10 reloads is about the end of the world for me. Perhaps it is my particular rifles chamber?


Posted By: britrifles
Date Posted: July 26 2022 at 7:52am
My match load is PPU Case (or Canadian Service Mk VII Ball case), 40.0 gr Varget (ADI AR2208) and 174 grain Sierra Matchking.

I think the largest single factor in case life is headspace.  That controls how much plastic strain the case experiences in the web area that is unconstrained by the chamber.  I keep my rifles at minimum  headspace, just over 0.064 inches.  None of my rifles will lock up on a 0.070 gage, bolt handles typically half inch from closing on the 0.070 gage.  

I also think neck sizing is essential to long case life, to keep the case head up against the bolt head.  But, you don't want to have excessive force to close the bolt either.  Some light pressure on the handle to fully lock the bolt is OK.   

Just my experience, others may have a different experience...



Posted By: Smokey
Date Posted: February 20 2023 at 3:30pm
I like to start out with unfired brass. I use a very mild load, just enough to swell the case to the chamber. I also commit an unspeakable act with those loads, I grease them. The entire case slides back up against the bolt face with no stretching. After I clean off the grease. The cases are then used as a wildcat cartridge setting the resizer so as not to set the shoulder back. I also use a LEE collet die much of the time.

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The thief may possess something he stole, but he does not own it.
The owner has a right to take his property back from the thief.


Posted By: britrifles
Date Posted: February 20 2023 at 5:31pm
Smokey,

According to Reynolds, every No. 4 action was proof tested with a “lightly oiled” proof round.  So, I think a greased case with a very mild load would not do any damage.  You would have to use an appropriate powder for reduced charges, otherwise an overpressure could occur.

The problem is you really don’t know how much load is being put on the bolt, and what the cumulative affects may be.  If your load produced only 50% of the maximum rated cartridge chamber pressure, say 22,500 CUP, likely no problem. But we don’t have any definitive data of how much additional load is applied to the bolt from an oiled case.  

How many “full power” reloads do you typically get with your method of fire forming the case?  I say “full power”, meaning something between min and max published load data for jacketed bullets and not reduced loads or cast bullet loads. 






Posted By: Stanforth
Date Posted: February 21 2023 at 8:20am
I have used PPU cases for years and owing to a shoulder injury I use a light, usually the manufactures Staring load.
 I have NEVER had a PPU case separated but i get case separated after about 2 reloads with Winchester.
If I get (given) Winchester cases I dump them or give them to someone I don't like.


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Life.. a sexually transmitted condition that is invariably fatal.


Posted By: britrifles
Date Posted: February 21 2023 at 12:00pm
My regular match load is 40.0 grains of Varget with 174 gr SMK.  That's a mid-range load for .303 per Hodgdon on-line data, I get about 2400 fps 20 feet from the muzzle.   

I've started tracking the number of reloads of PPU cases in two of my No. 4 rifles, but this first batch shot from my Mk 1/3 Long Branch, I don't know how many reloads on them, perhaps 40ish; with the first indication of cracking in the web. 

Stanforth, do you have an idea of how many reloads on your PPU cases?  

 



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