6BR neck separation

Slate264

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  • Jun 19, 2019
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    Hello everyone, looking for advise regarding neck separation.
    These are the specifics:
    -Lapua Brass, 27 inch barrel
    -3-4 firings, no annealing

    -Overall length grew by 2-3 thou, no trimming

    -30.5 gr of shooters world precision pushing 105s at 2860(barrel sped up after last match)

    Running one thou neck tension with .268 bushing

    -bumping shoulder 1-2 thou
    Seems like the split is starting from neck shoulder junction.
    Any help with this would be appreciated
     

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    Supersubes

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    Those look oddly uniform. Along with lash’s question above, do you have any virgin brass to look at from that lot? Did this just show itself now, or did it develop from the first firing?

    While unusual from Lapua, only time ive ever seen a shape like that it was a manufacturing defect.
     
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    AIAW

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  • Aug 16, 2001
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    Why no annealing? That's not neck separation, that's simple splitting. Only 4 things usually cause that: Pressure, work-hardened brass, cheap brass or a chamber abnormality. I doubt it's faulty Lapua brass - and Lapua is top notch. You velocity doesn't seem that crazy (although I am unfamiliar with that powder pressure curve). That leaves pressure, chamber defect and work-hardening.

    What do the spent primers/case head look like?
     

    Slate264

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  • Jun 19, 2019
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    How are you sizing your necks? How much does the neck reduce in the full length sizing die?
    Using a .268 bushing, in a Redding full length bushing due. I believe the fired neck measured .272. What’s odd is that second picture also shows split on the shoulder area?
     

    Slate264

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  • Jun 19, 2019
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    Those look oddly uniform. Along with lash’s question above, do you have any virgin brass to look at from that lot? Did this just show itself now, or did it develop from the first firing?

    While unusual from Lapua, only time ive ever seen a shape like that it was a manufacturing defect.
    I do have some new brass I can check out later. Iam almost sure it wasn’t there in the virgin brass. I noticed it after 3 firings or so
     

    Slate264

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  • Jun 19, 2019
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    Why no annealing? That's not neck separation, that's simple splitting. Only 4 things usually cause that: Pressure, work-hardened brass, cheap brass or a chamber abnormality. I doubt it's faulty Lapua brass - and Lapua is top notch. You velocity doesn't seem that crazy (although I am unfamiliar with that powder pressure curve). That leaves pressure, chamber defect and work-hardening.

    What do the spent primers/case head look like?
    Annealer is on its way…never annealed 6.5 creed Lapua brass and have close to 10 firings with no issues. Spent primers look good, still have roundness to them and bolt lift seemed fine too. No ejection marks on the case head.
    What kind of chamber defect would cause splitting like this? I had a chamber before that was nicked by the reamer and the brass came out looking very different from this. Thanks
     

    Supersubes

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  • Sep 6, 2006
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    Annealer is on its way…never annealed 6.5 creed Lapua brass and have close to 10 firings with no issues. Spent primers look good, still have roundness to them and bolt lift seemed fine too. No ejection marks on the case head.
    What kind of chamber defect would cause splitting like this? I had a chamber before that was nicked by the reamer and the brass came out looking very different from this. Thanks
    Whats the fired case neck diameter?
     
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    AIAW

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    Annealer is on its way…never annealed 6.5 creed Lapua brass and have close to 10 firings with no issues. Spent primers look good, still have roundness to them and bolt lift seemed fine too. No ejection marks on the case head.
    What kind of chamber defect would cause splitting like this? I had a chamber before that was nicked by the reamer and the brass came out looking very different from this. Thanks

    Just a suggestion on the chamber defect. They all present a bit differently (if that's even an issue). If you say that you got 10 firings with no issues then I doubt it is, especially where the failure is occurring. Perhaps check your sizing die while you are at it.

    A once-fired brass analysis would say a lot towards this. It's entirely possible that you just got a few bad pieces and nothing is really wrong at all.

    Have you been running the SWP powder for a while now or is that a new venture?
     
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    djarecke

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    Whats the fired case neck diameter?
    Bingo. And who did the chamber?

    There is something seriously wrong somewhere to split necks in only several firings.

    Either that brass is bad (which I doubt), something is amiss in the reloading process (possible), or your chamber is jacked.

    How many rounds on this barrel? Has it ever done this before?
     
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    918v

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    Looks like a manufacturing defect in the form of folded brass to me. I have formed 22-250 brass from 243 and some of the cases looked like that.
     
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    Slate264

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  • Jun 19, 2019
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    That looks like a die/bushing issue, since the lines are perfectly straight. Are you sure there isn't a burr of something in your neck bushing?
    I don’t think so, but I’ll double check again
     

    Slate264

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  • Jun 19, 2019
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    Just a suggestion on the chamber defect. They all present a bit differently (if that's even an issue). If you say that you got 10 firings with no issues then I doubt it is, especially where the failure is occurring. Perhaps check your sizing die while you are at it.

    A once-fired brass analysis would say a lot towards this. It's entirely possible that you just got a few bad pieces and nothing is really wrong at all.

    Have you been running the SWP powder for a while now or is that a new venture?
    Sorry, to clarify. 10 firings we’re on a different chamber and different cartridge. SWP is a new venture for me together with 6br cartridge. Been running 6.5 creed for few years before
     

    Slate264

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    Bingo. And who did the chamber?

    There is something seriously wrong somewhere to split necks in only several firings.

    Either that brass is bad (which I doubt), something is amiss in the reloading process (possible), or your chamber is jacked.

    How many rounds on this barrel? Has it ever done this before?
    About 400 rounds on the barrel. First 100 rds were fired with a light load
     

    Slate264

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    Looks like a manufacturing defect in the form of folded brass to me. I have formed 22-250 brass from 243 and some of the cases looked like that.
    Thanks, after how many firings?
     

    AIAW

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    Sorry, to clarify. 10 firings we’re on a different chamber and different cartridge. SWP is a new venture for me together with 6br cartridge. Been running 6.5 creed for few years before
    Ok, so just remember that only things we see from that particular rifle and current chamber are of interest in diagnosing a potential issue here.
     
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    Slate264

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    Just to add another variable to this mystery. Iam getting a powder soot on the shoulder area after firing, maybe every third round. Not sure if it has anything to do with this, just thought I would throw it out there
     

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    918v

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    Thanks, after how many firings?

    Zero. The fold is created during the process of forming the neck and shoulder. I think in your case it was concealed by the annealing discoloration and you didn’t notice it till now. It should not affect anything until it splits. And it could go on for 20 reloads like someone else mentioned earlier. I would monitor but not lose sleep over it.
     
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    Slate264

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  • Jun 19, 2019
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    Zero. The fold is created during the process of forming the neck and shoulder. I think in your case it was concealed by the annealing discoloration and you didn’t notice it till now. It should not affect anything until it splits. And it could go on for 20 reloads like someone else mentioned earlier. I would monitor but not lose sleep over it.
    Got you, but if you look at the second picture I posted with 1 case, it looks different and there is a split already on the neck and shoulder. Confused..I’ll keep monitoring the other ones. Thanks
     

    Tzadkiel

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    Just to add another variable to this mystery. Iam getting a powder soot on the shoulder area after firing, maybe every third round. Not sure if it has anything to do with this, just thought I would throw it out there
    I think thats pretty normal, I get some weird results with powder fouling on cases with different bullets. I shoot 68g berger flat bases at 100yd and only part of the neck will foul, and i shoot 65g berger boat tails and 70gr sierra blitzking boat tails at 200 and 300yd and it will foul the neck and shoulder I am on about 25 reloads on my 6br lapua brass with no annealing but i only neck size. I have only split 2 in that time similar to yours half in the shoulder and half in the neck, and one super weird accident when somehow alot of pressure went past the neck and folded the shoulder in on itself.
     
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    lash

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    Okay. Your picture with the carbon at the shoulder is a hint in my opinion. It looks like for starters, that you are sizing those necks down 0.004”, which is too much. Combine that with the thick necks typical on Lapua brass and two things are happening. First the case neck is not expanding enough to seal the chamber, due to the 0.004” smaller dia. That is also causing the brass to be worked too much under pressure, which could cause stress cracking.

    Your sizing die should be honed out a bit to reduce the amount of neck sizing. It also sounds to me like at least this batch of brass should be annealed before sizing again.
     

    Slate264

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  • Jun 19, 2019
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    Okay. Your picture with the carbon at the shoulder is a hint in my opinion. It looks like for starters, that you are sizing those necks down 0.004”, which is too much. Combine that with the thick necks typical on Lapua brass and two things are happening. First the case neck is not expanding enough to seal the chamber, due to the 0.004” smaller dia. That is also causing the brass to be worked too much under pressure, which could cause stress cracking.

    Your sizing die should be honed out a bit to reduce the amount of neck sizing. It also sounds to me like at least this batch of brass should be annealed before sizing again.
    When I measured the diameter of the loaded new round , it measured .2695. I went with .268 bushing for the 1.5thou tension. So now the fired neck .272, should I go with .270 bushing?
     

    Supersubes

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    When I measured the diameter of the loaded new round , it measured .2695. I went with .268 bushing for the 1.5thou tension. So now the fired neck .272, should I go with .270 bushing?
    No you shouldn't use a .270. If your measurements are correct, the numbers are fine. Its possible that your Redding bushing is wrong, as they frequently are. Its incorrect to just pick a bushing, and assume the neck ends up there. You need to measure the sized neck and compare that to the loaded neck diameter, thw result is your neck tension. All of that has nothing to do with your issue imo.
     

    Supersubes

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    I feel like we’re talking around in circles here due to assumptions, and having to pry details out of the OP. @Slate264 did you measure the fired necks, are do you write .272 because that what your chamber is “supposed” to be?

    Are all of your 3-4x fired cases like this, or are the pictured cases the only ones?

    Have you gone through the remaining virgin cases yet to find wrinkles?
     

    918v

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    Okay. Your picture with the carbon at the shoulder is a hint in my opinion. It looks like for starters, that you are sizing those necks down 0.004”, which is too much. Combine that with the thick necks typical on Lapua brass and two things are happening. First the case neck is not expanding enough to seal the chamber, due to the 0.004” smaller dia. That is also causing the brass to be worked too much under pressure, which could cause stress cracking.

    Your sizing die should be honed out a bit to reduce the amount of neck sizing. It also sounds to me like at least this batch of brass should be annealed before sizing again.

    Just erase it all
     

    Slate264

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  • Jun 19, 2019
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    I feel like we’re talking around in circles here due to assumptions, and having to pry details out of the OP. @Slate264 did you measure the fired necks, are do you write .272 because that what your chamber is “supposed” to be?

    Are all of your 3-4x fired cases like this, or are the pictured cases the only ones?

    Have you gone through the remaining virgin cases yet to find wrinkles?
    I measured the neck a while ago, and I believe it was .272. Chamber is .274.
    So far I found 7 cases with the similar issue out of 125.
    Haven’t looked at the virgin brass yet, will do it later tonight.
    Thanks for your help
     

    smoothy8500

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    The fold is created during the process of forming the neck and shoulder. I think in your case it was concealed by the annealing discoloration and you didn’t notice it till now.
    4-5 years ago I had a batch of 200 Lapua 6BR with several cases presenting those folds/creases. They were a little more obvious when I opened the boxes and inspected them. I just tossed them.
     
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