First Indication of a PPU Case Head Separation
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Category: Reloading
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Printed Date: January 30 2023 at 5:57am
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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
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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.
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Replies:
Posted By: Shamu
Date Posted: June 12 2022 at 12:13pm
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Yep that's the classic symptom! ------------- 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
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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
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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
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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 ------------- DaveNo5 |
Posted By: Shamu
Date Posted: July 25 2022 at 11:42am
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Here you go. I crushed the case mouths to prevent others fishing them out of the trash at the rage & tying their gun up.   ------------- 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
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I've had a couple go there. This odd positioning seems unique to the Remington nickle-plated I got a bunch of years back. ------------- 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
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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
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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... |