Help determining actual incipient head case seperation signs

Discussion in 'Reloading' started by DartonJager, Aug 5, 2018.

  1. DartonJager

    DartonJager Well-Known Member

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    Since I started to full length resize my brass VS neck, I'm getting the common shiny ring around my brass just ahead of the case head due to FL/RS and are wondering how one tells the difference from a ring from FL resizing and case stretching so I will be able to scrap a piece of brass and avoid suffering a case head separation incident. I use a stainless steel dental pic(the type used to clean teeth) to check the inside of my brass at the suspect area of the case head, but as I never have actually found apiece of brass that had stretched to the point of nearing case head separation, I'm not exactly certain what it should feel like. When I check I first run the pic on the inside of a new never fired piece of brass and then the fired pieces of brass in hopes it will allow me to recognize by feel any difference in the brass due to stretching, but as I have yet to actually find a piece of brass that has felt different to the point I'm sure it has stretched I'm concerned my brass will still be safe to reload once the number of times fired gets above 4 or 5x.

    YouTube videos are awesome VISUAL aids but not so much when it comes to tactile aid.

    Thanks,
    DJ/Art.
     
  2. Barrelnut

    Barrelnut Well-Known Member

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    I use a dental pic and a straightened paper clip. Sometimes I like the paper clip better as it flexes easier and I can get a better feel sometimes.

    I push the tool down until it bottoms out on the case head and them pull back slowly without a lot of firm pressure on the tool. If you feel a small valley, that is where the brass is starting to thin. It is subtle, but you can feel it. I push/pull the tool back and forth lightly over the area when I suspect I feel an area that is thinning. It is like a small depression and will not really grab the tool, but you can feel the depression. This depression will not necessarily be all the way around the case either. Now, if the depression does grab the tool, that means the case is very worn and could separate on the next firing. When I feel the depression on a case I like to cut it open with a dremel and have a look.

    I keep all of my cases sorted by the same firing in groups of 50, Once I find a case wearing, I toss all 50. I can get 10 firings out of Hornady Creedmoor brass, but have had a few too close to separating at 10 firings. So how I toss them after 8 firings.

    A case that is close to separation will have a shiny ring just above the web on the outside. Once you see the shiny ring on the outside, your tool will probably start to grab on the depression on the inside. The ring will be just above the small shiny rings on the web you get when FL sizing a case. It will look more like a scratch. You will probably be able to feel it with your fingernail. It will not be the same all the way around the case either. It will not be a perfect ring that is the same distance from the base either. It will dip lower in some spots. This is because the web is not exactly the same thickness all the way around.

    RCBS or Redding has a gauge you can use to measure the thinning of the web. I don't see a need for that tool though, since once you get a feel for things with the dental pick, it is easy and faster.

    I also have a borescope, so sometimes I put it in the case after I have cleaned the cases. You can see the depression that way sometimes too.
     
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  3. bigedp51

    bigedp51 Well-Known Member

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    I collected old milsurp rifles and used the $100.00 bent paper clip below to measure case stretching and thinning. (RCBS case mastering gauge)

    [​IMG]

    Below a factory loaded Winchester .303 British case that stretched and thinned .009 on the first firing. And with a bent paper clip I was not sure if I felt the thinning or not and why I bought the RCBS gauge. Old milsurp rifles can have long fat chambers and be hard on brass.

    [​IMG]

    Below on the far right is a .303 case that was full length resized and fired twice. This case did not split and leak but you can see is ready to totally split.

    [​IMG]

    Below a .303 case that split but did not have a total case head separation.

    [​IMG]

    Below a Hornady cartridge case headspace gauge and a very good tool for measuring new, fired and resized cases.

    [​IMG]

    Bottom line, if you know the headspace of your chamber and size your cases with minimum shoulder bump your cases should not stretch and thin.

    Below it is your head clearance with new cases and resized cases that determines if your cases stretch beyound their elastic limits.

    [​IMG]

    [​IMG]
     
    Last edited: Aug 6, 2018
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  4. gohring3006

    gohring3006 Well-Known Member

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    Got any pics? How far above the rim is the suspected area?
     
  5. Kansaswoodguy

    Kansaswoodguy Well-Known Member

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    Just bump the shoulder .003 and you be fine I’ve only ever gotten head separation if I’m over working my brass by bumping the shoulder to much.
     
  6. tbrice23

    tbrice23 Well-Known Member

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    Bisect one. 20150716_143402_001-2.jpg l cut one in half when I have about 7 full length sizing cycles ( bumping shoulders .002").

    The one pictured had ten sizings.
     
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  7. RT2506

    RT2506 Well-Known Member

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    I know that you are using this as an example but the 303 British rifle was designed with over size chambers so they would shoot in the mud blood and the beer. If you want cases to last and really get the accuracy potential out of these old war tools keep your cases separated as to which rifle they were shot in and neck size the case and the cases will last a long time.

    As for the OPs problem, you may have a little large chamber or your sizing die may just size a little too tight. When I have run into this problem I back off the size die a little and do what I call a part size. Really only neck sizing with a FL die. Test the amount of sizing you need and then lock down the die at that point.
     
  8. bigedp51

    bigedp51 Well-Known Member

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    Thank you RT2506 I learned the hard way in what you said above in the 1970s and collecting and shooting milsurp rifles. At maximum military headspace on the .303 British Enfield of .074 and a rim thickness of .058 you will have .016 head clearance.

    And on these rimmed cases you could slip a thin rubber o-ring around the case to hold it against the bolt face to fire form the cases. This prevents the case from stretching on the first firing and thereafter you neck size only, and let the case headspace on its shoulder.

    [​IMG]

    [​IMG]


    The secret to long case life is being able to measure the fired cases shoulder location and using minimum shoulder bump.

    The picture below is worth a thousand words, when full length resizing you only want to push the shoulder back .001 to ,002 below the red dotted line. The closer to the green dotted line you push the shoulder the more the case will stretch and thin and cause a case head separation.

    [​IMG]

    NOTE, if you make a workup load starting at the suggested start load and work up, you will find the point the primers are flush with the base of the case. It is at this point the pressure is great enough to make the case stretch to meet the bolt face. Below this pressure point you can load new cases with the bullet jammed into the rifling or make a false shoulder to form them to the chamber without any case stretching.
     
    Last edited: Aug 7, 2018
  9. MNbogboy

    MNbogboy Well-Known Member

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    +2 on all responses.
    Without seeing pictures from the OP it is hard to say whether or not he is experiencing "IHS".
    Most of us have learned the hard way long before internet! I applaud the OP for being proactive with this matter.
    My advice is to make sure to set the full length die to .002 "bump".
    One of the most common mistakes that "new" reloaders make is to set fl dies according to the instructions that are shipped with the die! They work but one size fits all is not optimal.
    Btw I made a tool by heating up the tip of a flat screwdriver and bending a tight 90 at the tip. Then shaped it with a small file. You can really "feel" imperfections with it. But with proper die setup there is barely a need for it anymore.
    Randy
     
  10. dok7mm

    dok7mm Well-Known Member

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    You're right Randy, not only they don't setup the die correctly, they start bumping the shoulder before the case is fully formed to their chamber. I recently helped a guy who was actually bumping shoulder .006" when his target was .003". He set it once, and left it, for use on two different rifles.
     
  11. bigedp51

    bigedp51 Well-Known Member

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    You have to separate neck sizing from full length resizing and how many firings it takes to fit the chamber.

    When you full length resize the case grows in length as it is squeezed and you can make the case longer than the chamber.

    This is the vary reason with Redding competition shell holders they tell you to start with the +.010 and work down.

    The illustration below shows the case shoulder being squeezed forward and then being pushed back. Meaning when full length resizing the vast majority of the time the case only needs to be fired once.

    [​IMG]

    Before the Redding competition shell holders we used feeler gauges and adjusted the die downward until the case chambered freely. And I'm sure there are reloaders out there who remember doing this and not being able to close the bolt until thinner feeler gauges were used.

    [​IMG]

    And I'm also sure there are people out there who used a full length die to partially full length resize the cases because they didn't have a neck sizing die. And know the case body was not reduced in diameter enough to squeeze the shoulder forward.
     
  12. Ckgworks

    Ckgworks Well-Known Member

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    I dug around in my old brass bin and found this example.....I use a piece of wire with a bent 90 on it, and make sure the end has a sharp edge. If I feel something funny, I use my fingers to make a stop at the case neck, and pull wire out. If you lay wire on the outside, the end will line up with the ring, just to confirm location. If it would help you, I'll send you this piece of brass, so you can feel what bad is. ;) The others explained much better than I could about how to avoid it!
     

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