F T/R Competition Brass failure

X

XTR

F-TR junkie
Full Member
Minuteman
    • Sep 4, 2010
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    Lebanon, NH
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    #1
    Just things to watch for. We tend to push our loads a little hard. This is an "almost a problem" picture.

    Case head separation, but not quite.

    Winchester Brass, (BHA headstamp) Fired 5X I've noticed that more of this batch is showing some visible wear in the same area after this firing. The scribe line on this one grabbed my attention but if you look closely (why I took the shot with my Nikon) you can see the stretch on both sides of the line. That is what is noticeable in some of the other brass in this batch. Time for this batch to go to recycle.

    1_09_04_12_3_08_41.jpg


    Pushing 175s over 44+ Varget.

    Oh yea, one more reason to always wear shooting glasses.

     
    #2
    Re: Brass failure

    Might want to consider this article by German Salazar, several more issues than just pushing a load, cause case head seperations.


    http://riflemansjournal.blogspot.com/2010/05/reloading-case-head-separations.html

    "A frequently expressed misconception about case head separations is that they result from excessive pressure. That is not correct. Pressure, of course, overcomes the strength of the brass case and causes the separation, but that will not happen unless and until the case has thinned excessively through the mechanism described above. Repeated cycles of case sizing with the resultant growth and thinning create the condition which allows normal pressure levels to separate the case at the thin spot. A new case would only separate in a rifle with grossly excessive headspace and one is not likely to encounter a professionally gunsmithed match rifle with that condition."
     
    #3
    Re: Brass failure

    My internet connection is terribly slow but there was a discussion about this problem and Winchester brass in particular a few months ago. Look for a thread in either the gunsmithing or reloading section started by CDixon I believe. If my connection was a bit better, I'd dig it up myself for you.

    Long story short, Win brass isn't quite right, a touch small in diameter right above the case rim. I doubt you have an oversize chamber or are sizing your brass too much.

    Geb
     
    #4
    Re: Brass failure

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Unsichtbar</div><div class="ubbcode-body">Might want to consider this article by German Salazar, several more issues than just pushing a load, cause case head seperations.


    </div></div>

    I'm familiar with why it happens and I didn't mean to imply that it was a "pressure only" thing, but for folks that are pushing it will happen sooner. If I was loading at 43gn of Varget and shooting bullets at 2600FPS I would probably get a dozen reloads before I had a problem.

    This wasn't intended to be a "this is a pressure sign" post, more of a "watch for signs of this in your brass because it means that it is about to fail" post.
     
    #5
    Re: Brass failure

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gebhardt02</div><div class="ubbcode-body">My internet connection is terribly slow but there was a discussion about this problem and Winchester brass in particular a few months ago. Look for a thread in either the gunsmithing or reloading section started by CDixon I believe. If my connection was a bit better, I'd dig it up myself for you.

    Long story short, Win brass isn't quite right, a touch small in diameter right above the case rim. I doubt you have an oversize chamber or are sizing your brass too much.

    Geb </div></div>

    It is a custom chamber and I neck size only, so no, it's surely not a "too much resizing" problem.
     
    #6
    Re: Brass failure

    Something is not adding up IMO was it new brass fired in you rifle,no hard bolt lift, were primer pockets loose after 5 firings, measurement of extractor ring is it much over .405

    The reason for asking is have been several people that have had case head seperations in Winchester Bass in the last month or so.. custom chamber necked size only, case head seperation should not have occured. Primer pockets blown yes
     
    #7
    Re: Brass failure

    no loose pockets.
    Extractor ring is .403

    At the line it is 0.469, an unfired BHA* is 0.460 at the same point.

    Just forward of the extractor ring as close as I can get with calipers is 0.464 on this case and 0.463 on an unfired BHA*.

    * BHA uses WW brass. The failed brass actually has a BHA head-stamp.
     
    #8
    Re: Brass failure

    A good indication that the load is hot and causing this is how much the case grows in length in each firing when working with cases like the 308 having a relatively shallow shoulder angle.

    The brass has to be going somewhere in order to thin in the web. The brass flows forward upon firing.

    I once measured a 30-06 load that grew 15 thou in one firing - that brass was done in 2 firings. For sure a high pressure load.

    On the subject of "neck sizing only", it is possible to push the shoulder back with a neck-only die if mis-adjusted. The shoulder is pushed back from the neck/shoulder junction, rather than the whole shoulder as you would with a bump die or FL die.

    Even a correctly adjusted neck-only die can change the headspace, as German points out in one of his articles (and I too have experienced), generally making it LONGER and harder to chamber...
     
    #10
    Re: Brass failure

    I have two hundred case right now with these exact same thing happening to them on the fifth firing of them. they are Hornady .308 match brass on the 6th firing. Running 44.5gr RL-15 with CCI BR2 primer under a 178 amax. No loose primer pockets though.

    Sounds about right to me!
     
    #11
    Re: Brass failure

    When I buy new brass I FL resize before I use it the first time, then I collet size it.

    This was a batch of once fired when I got it, and has been FL resized twice. Once upon receipt and then once after 3x, to make a long story short I fired some of my match loads in my hunting rifle with stock chamber. After neck sizing they stuck in my match rifle but I didn't know which were which so after about 3X all cases went into the FL body die.

    I use a Lee collet for necks. After I did the FL bodys at 3X I bumped shoulders .003 with a Forster bushing bump.

    All were trimmed to 2.010 after the 3X prep cycle.



    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KHOOKS</div><div class="ubbcode-body">I have two hundred case right now with these exact same thing happening to them on the fifth firing of them. they are Hornady .308 match brass on the 6th firing. Running 44.5gr RL-15 with CCI BR2 primer under a 178 amax. No loose primer pockets though.

    Sounds about right to me!</div></div>

    I wasn't surprised at all, I started sticking the bent paper clip in a sampling after the 4th firing looking for a notch. Haven't felt it before but this one it's pretty distinct.

    I don't know how many of you are shooting F-TR. Factory BHA match stuff is supposed to shoot at about 2600 to 2650, I'm loading 175s to 2750+ and 185 LRBTs to over 2700. I know they are hot. I've also done some load work with 155s that I pushed to 3000FPS. I'm not at all surprised here.

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: _9H_Cracka</div><div class="ubbcode-body">A good indication that the load is hot and causing this is how much the case grows in length in each firing</div></div>

    It was trimmed to 2.005 after 3, after 5 it is at 2.009. I measured two other cases that have been fired 4x and they are at 2.007.

     
    #12
    Re: Brass failure

    Thanks, the history of the brass makes more since of why the brass failed after 5 firings. I have .308 brass shot more than 20 times, with loads that are stiff but not over the line, but close to it.
     
    #13
    Re: Brass failure

    <div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">This was a batch of once fired when I got it, and has been FL resized twice. </div></div>

    Was the first firing out of an M14/M1A?
     
    #15
    Re: Brass failure

    I shoot 175's with 44.8 grains of Varget and I have never seen that, even on Federal cases. I wonder if the neck-sizing has anything to do with it. It seems like the brass has to go somewhere, and with the neck-sizing it cannot blow out, and only expand lengthwise.
     
    #16
    Re: Brass failure

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: XTR</div><div class="ubbcode-body">
    1_09_04_12_3_08_41.jpg
    </div></div>
    I see case seperation a lot when I push the shoulders back to far when resizing. I haven't had that happen yet with hot loads. Thats when I normally see ejector marks and blown primers.
     
    #18
    Re: Brass failure

    XTR, sounds like you had a bad piece of brass, if others in the batch are not following suit. You should be able to use a bent paper clip and feel the web of the others. If there is no indication of a groove, I'd keep shooting them.
     
    #19
    Re: Brass failure

    I've pondered this for a while now and something occurred to me, I've never measured the shoulder before and after sizing the way I have my Lee Collet set up. I checked it this morning and at most the shoulder moves .0005, and that's the limit that my calipers can see.


    One other possible variable, for whatever it is worth. I've got 2 batches of 4X fired brass. Half of it was fired 4x in my old barrel and half was fired 2x or 3x in the old barrel and then 1x or 2x in my new barrel. I've checked the shoulders on both and it looks like the shoulder on my new barrel is .002 longer than the old one. (I know the old one was tight) This one came from the 4x in the old barrel before being fired in my new one.

    This time of year I shoot up a few hundred rounds a month between practices and matches.

    I did cut the case in half. Not sure the pic is worth posting. It looks a whole lot like the last pic in Germán A. Salazar's article linked above except that I do ultrasonic cleaning so it's a good bit cleaner inside after firing.

    Honestly, I think it's just that the brass wore out, it is going to happen eventually especially if you are pushing stiff loads. The real point of this thread is to remind those guys that are running a lot of reloaded rounds down the tube is to watch and just another reminder that glasses are more than just a good idea. (20 yrs ago I dropped the hammer on a 45ACP with a double charge of Win 231, it took 3 more yrs to get all the metal out of my face and I had to throw away my glasses. Lesson learned)
     
    #20
    Re: Brass failure

    Well the load does not sound all that stiff and the brass is not growing at an accelerated rate, hence my reasoning for the single bad case.

    Now that you post you are are shooting the brass in different chambers cut with different reamers to different headspace dimensions, you've got your answer right there...

    Look at the information in your first post versus what else you have revealed in the course of this thread. If nothing else, going through this dialogue has helped you reason through all the factors effecting your F/TR loads.

    You've demonstrated first hand why many serious shooters buy their own reamer and have one competent gunsmith do all of their work.
     
    #21
    Re: Brass failure

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: _9H_Cracka</div><div class="ubbcode-body">
    Now that you post you are are shooting the brass in different chambers cut with different reamers to different headspace dimensions, you've got your answer right there...

    ...

    You've demonstrated first hand why many serious shooters buy their own reamer and have one competent gunsmith do all of their work. </div></div>

    I'm not certain that the difference in chambers has too much to do with it. I posted it in the interest of full disclosure but I don't think I'd read to much into it. The stresses on the brass caused by one firing in a new chamber is pretty low. The difference between the two is less than the stress caused by FL resizing, and the .002 headspace difference really just equated to bumping the shoulder after 4x which isn't uncommon.

    As to the reamer, I get that part. I'm getting one, actually two, one for 308 and one for 708.

    Although now I do see the case for the guys who use their reamer to get a sizing die made.
     
    #22
    Re: Brass failure

    When I see brass like that I immediately think the shoulder has been pushed back too far. The cause of a lot of shoulders being pushed too far back are the die instructions that have you set the headsapace by bottoming out the die and backing out 1/4? turn. Get a gauge for measuring the amount of set back before setting a die up. Or better yet have a gauge made with your barrel stub and reamer tha next time rebarreling. Having the gauge made with your reamer and barrel stub also gives you a great way to measure seating depth with respect to lands.

    wade
     
    #23
    Re: Brass failure

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">at most the shoulder moves .0005</div></div>

    That's a lot of shoulder bump. The brass has to go somewhere, so your cases are thinning as they stretch.

    I believe 2 to 3 thousandths is considered enough so that you're not unduly stretching your cases. </div></div>

    .0005 is half a thou Dave.
     
    #24
    Re: Brass failure

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">at most the shoulder moves .0005</div></div>

    That's a lot of shoulder bump. The brass has to go somewhere, so your cases are thinning as they stretch.

    I believe 2 to 3 thousandths is considered enough so that you're not unduly stretching your cases. </div></div>

    Check the decimal place... he's saying it moves <span style="font-weight: bold"><span style="font-style: italic">half</span></span> a thou...

    Whoops. Ninja fingas beat me to it
    wink.gif
     
    #25
    Re: Brass failure

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">at most the shoulder moves .0005</div></div>

    That's a lot of shoulder bump. The brass has to go somewhere, so your cases are thinning as they stretch.

    I believe 2 to 3 thousandths is considered enough so that you're not unduly stretching your cases. </div></div>

    sinister, I think you missed a zero there. The setback is 0.0005, that's half a thousandth, not 0.005 or 5 thousandths.
     
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