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Thread: split necks

  1. #1

    Default split necks

    a friend of mine gave me 100 once fired nickel plated 300 win. short mag. cases. his gun was a win. model 70 I shoot a browning xbolt don't know if that matters or not. after two loadings the necks are starting to split. 50 out of 100 are split. never had this problem with brass cases. i'm not close to a max load. any ideas?

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    get out your butane torch and anneal the case necks before you reload... firing (and reloading) has hardened the brass through working (stretching) and heating. Heat them up good and allow to air cool slowly, concentrate on the neck portion only. This should return your brass to a more malleable state. My $.02

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    Member dkwarthog's Avatar
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    I am not an expert, I have only done some research into annealing case necks...but from what I have read, if you want to diy annealling, I would recommend you put the cases neck up in a pan of water so the water is below the shoulder and heat the necks that way. Then when they get "hot enough" (I'm not recommending a temperature, but I hear "just red enough to see the glow in a dim room") then tip them over into the water. The water acts as a heat sink to keep from over heating the necks which is bad as well.


    All that said, I would dump the nickel brass and get some real brass brass...JMO..

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    Annealing is supposed to be precision work. They make some indicating products that melt when they get enough.

    With that said I would be pitching that batch of shells.

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    Actually, I mispoke and it's too late to edit my post. What I meant to say was that the water acts as a heat sink to keep from heating the cases below the necks. In other words, you dont want to change the properties of the case wall and base area.....

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    I don't believe that twice fried cases are work hardened. Hundreds of us on here load several times and very few ever anneal. Annealing is good but it won't solve your issues based on your comments. Also annealing is a delicate operation and must be done correctly or your brass will be ruined.

    If you are splitting 50% of your necks something else is wrong!

    Using the brass in question measure the outside diameter (OD) of your re-sized brass at the neck. Do the same with that brass after the bullet is seated. I'm wondering how much your re-size die is working your neck. A .002 difference would be about right. Production tolerances are generally up to .004 in this area.

    Bench rest guys running match chambers keep that difference down to .001-.002, this is one of the reasons they neck turn. Meaning they keep an exact neck wall thickness and bullet interference so they can control neck tension and insure proper clearance at bullet release. Less than .001 would cause huge pressure spikes because the bullet would be held tight by a neck that had no where to expand to.

    Measure the OD of a fired case. The difference between the loaded case OD and the fired case should be less than .005, if not I'm thinking you have a sloppy chamber. This will excessively work your necks and cause splits in a short time.

  7. #7

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    I measured the neck on the sized case its .332 with seated bullet its .336 the cases will be in the trash in the am

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    Quote Originally Posted by bearman8 View Post
    I measured the neck on the sized case its .332 with seated bullet its .336 the cases will be in the trash in the am



    Not so fast, that is the sizing die squeezing them down and the bullet pushing them back out. That is the interference fit or tension.

    A more important measurement is the loaded OD and the fired OD. The difference should be .002 - .004 on typical rifles and .001-.002 for the tight chamber bench rest crowd that neck turns their brass to exact tolerances.

    If the difference is more than .005 this would be a loose necked chamber and that would work your brass to a hard condition faster. Less than .002 could cause pressure spikes if your brass flowed into the neck and thickened it. The thicker brass could be turned down if you choose to do so. If not and the clearance was reduced to .001 or less pressure would spike.

    Just curious, what brand of brass are you dealing with?

    Most quality brass has a wall thickness between .012-.014, some others are as thin as .010 and that can cause excessive play in the chamber neck area too. I've measured some Federal that was .015 thick after a few firings. That can reduce chamber neck clearance and cause pressure spikes.

    The thicker walled brass can also have a tighter neck clearance because the sizing die will make the OD the same on all cases, thick or thin. The thicker ones would then have a bigger OD once seated. This can be cured by neck turning and annealing but not worth the effort on plated cases that have a prior perhaps unknown history.

    Isn't forensic finding reloading fun...

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    The numbers I posted in the earlier posts are typical clearances within production rifles using typical dies and average wall thickness brass. This information was retrieved from one of the books that I've read on some of the issues associated with reloading and chamber clearance problems caused by thick brass, thin brass or poor chamber specs.

    Just for grins I went out in the shop and grabbed a few samples to check this out with two of my production Rugers versus a custom built long range rifle built by a reputable accurate rifle manufacture.

    For reference from left to right prepped, loaded and fired I've selected a .243 Win, .308 Win and 338 Lapua Magnum, all bullets are Berger. The .243 uses Winchester brass, the .308 and .338 use Lapua brass. The wall thickness of the virgin Winchester is .0135, the .308 is .013. The four times shot .338 brass is .014, some brass flow thickening the neck has occurred. The 338 brass was annealed on the forth re-size but no neck turning to date.

    The .243 sized neck OD is .267, the seated OD is .270, the fired case neck OD is .275, this fits typical design specs.

    The .308 sized neck OD is .333, the seated OD is .335, the fired neck OD is .339, this also fits within typical production design specs.

    Imagine if the above cases in the production rifles had .015 wall thickness. In that scenario the seated OD versus fired OD would be about .001, that would be dangerous.

    I imagine production designs have a little more room to accommodate a variety of brass cases without excessive pressures that would be caused by tight specs.

    The .338LM is a match chamber and loaded with match grade dies. The sized brass neck OD is .362, seated neck OD is .364 and fired neck OD is .366. Neck turning will probably be required on the next prep to maintain an adequate seated neck to chamber clearance of .002 in this rifle.


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    I would like to know your wall thickness and the difference between seated and fired OD. That may point to a condition that could be causing your splitting. If not then I'm puzzled about the high percentage of failures that you have reported. Generally neck splitting isn't the first over pressure sign that shows it's ugly face. Perhaps the cases that you have acquired have a few more cycles than you suspect. I've reloaded several Federal nickel plated pieces for a buddy with a 375 H&H and they're holding up well with full power loads in a production Rem 700.

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    Thanks for the detailed response Marshall. I learned some new stuff again... Good luck to the OP, I'd be interested in finding out the cause of the neck splitting...

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    Itís the nickel causing it. Nickel work hardens much faster than brass and where the nickel cracks the brass cracks because that becomes the weakest place that moves most. Nickel is also very hard and cracked or pealing nickel plating has sharp edges that will scratch and ruin a die in one stroke.
     
    Anneal them often, inspect them closely often or chuck them. Annealing the pan method isnít hard, not any voodoo or anything to it just got to start doing to learn how it works.
    Now mettles other than steels anneal (soften) from quenching (cooling off fast) which is opposite steel that hardens from quenching.
    The pan method of annealing works great and is as dkwarthog described in post #3 here except he left out one important step. Once they are hot you need to knock them over so they quench and anneal. Stand them in a line in a pan of water that protects the head, ĹĒ to 1Ē deep. Heat a case at the shoulder with a plumbers torch until they just begin to glow in a very dark room, in a lit room they look waxy when you move the torch off them from the heat waves coming off but it takes doing to be able to see it. There are crayons that will help you learn to read the heat color but time and doing is the best teacher. Once each case is to heat you knock it over into the water and move on to the next one.
     
    There are many fancy annealing methods from folks making it more complicated than it is. You donít need to heat all around, the brass will conduct the heat all around just like soldering a copper pipe. Heat at the shoulder or just below the mouth on straight wall cases, this way the heat runs up to the thinner mouth and gets far enough down without melting the mouth. Go for it, youíll ruin some cases in learning but those cases are gonna split anyway without annealing so you have nothing to loose in learning your voodoo!
    Andy
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  12. #12

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    Quote Originally Posted by ADfields View Post
    Itís the nickel causing it. Nickel work hardens much faster than brass and where the nickel cracks the brass cracks because that becomes the weakest place that moves most. Nickel is also very hard and cracked or pealing nickel plating has sharp edges that will scratch and ruin a die in one stroke.
     
    Anneal them often, inspect them closely often or chuck them. Annealing the pan method isnít hard, not any voodoo or anything to it just got to start doing to learn how it works.
    Now mettles other than steels anneal (soften) from quenching (cooling off fast) which is opposite steel that hardens from quenching.
    The pan method of annealing works great and is as dkwarthog described in post #3 here except he left out one important step. Once they are hot you need to knock them over so they quench and anneal. Stand them in a line in a pan of water that protects the head, ĹĒ to 1Ē deep. Heat a case at the shoulder with a plumbers torch until they just begin to glow in a very dark room, in a lit room they look waxy when you move the torch off them from the heat waves coming off but it takes doing to be able to see it. There are crayons that will help you learn to read the heat color but time and doing is the best teacher. Once each case is to heat you knock it over into the water and move on to the next one.
     
    There are many fancy annealing methods from folks making it more complicated than it is. You donít need to heat all around, the brass will conduct the heat all around just like soldering a copper pipe. Heat at the shoulder or just below the mouth on straight wall cases, this way the heat runs up to the thinner mouth and gets far enough down without melting the mouth. Go for it, youíll ruin some cases in learning but those cases are gonna split anyway without annealing so you have nothing to loose in learning your voodoo!
    I think I will give it a try thanks

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    Andy is right, annealing isn't to difficult but it helps to receive a lesson from a buddy that does it right. Practice on some junk cases to get your timing right.

    I used this stuff the first few times:
    http://www.brownells.com/gunsmith-to...124.aspx#31621

    I've seen the tip over in the pan method in videos, seems reasonable.

    I use a five gallon bucket of water next to the bench and a long 3/8 drive extension with a deep socket that covers about 3/4 of the case length. I hold the extension with the case in the socket and put it in the flame then dump the case into the water. Heat the neck/shoulder junction as Andy describes taking care not to over heat. 650f-750f seems to be the most common temps agreed on. To hot and the case is ruined. Not hot enough and it won't anneal. The dim room trick is a good one. If you see a red case in a bright room you have it to hot.

    Have fun, you may salvage your cases assuming this is the issue.

  14. #14

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    thanks for the info I have some heat treating supplies from the days I did gunsmithing. I will be giving it a try this weekend

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    Sponsor ADfields's Avatar
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    Like everything it just takes some experimenting. Itís hard to over heat them much with the head sitting in water, brass is a very good conductor and water is a great heat sink sucking excess heat out and trying to boil off. After each batch I dump my pan into the wifeís noodle strainer and go with new cool water every batch.
    Andy
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  16. #16

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    I know there are more knowledgeable ppl out there than me...but i will not reload nickel. I would almost bet, you switch to actual brass, and you won't have this problem anymore

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    If its Winchester made brass I split it about 40% of the time on my second load and have a 90% fail rate with it on round 3. That's out if a 300wsm and not a hot load. I switch to Norma and am getting around 10 loads each w/o problem. The Norma is just thicker and better woven brass. I won't buy Winchester brass for anything again.

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    Quote Originally Posted by medic2022 View Post
    If its Winchester made brass I split it about 40% of the time on my second load and have a 90% fail rate with it on round 3. That's out if a 300wsm and not a hot load. I switch to Norma and am getting around 10 loads each w/o problem. The Norma is just thicker and better woven brass. I won't buy Winchester brass for anything again.
    Amazing, I've been acused of shooting hot loads before but I've never split a neck in any rifle ever. High pressure simply doesn't show up in the neck first. I would love to hear from Murphy on this topic.

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