How do you bump shoulder a couple of thou?

pell1203

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  • Dec 27, 2007
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    Hey guys, need a little help... I'm running .308 brass, originally prepped and trimmed to specs, that have now gone through 5 or 6 firings on the same rifle with only neck sizing in between. I noticed on this last pass that the bolt seemed a little harder to open and close on a handful of rounds. Not by a lot, but definitively noticeable. I've often read here that if you bump the shoulders back by a couple of thousands each time you neck size, you can effectively avoid this problem altogether.

    As background, I own a Redding T-7 press, Type S - Bushing Neck Sizing Die, Body Die, and Competition Seating Die. So far I've only used the neck sizing die and the seating die. I tried controlling the depth of the bushing on the neck sizer die by leaving anywhere from 1/16 of a turn for free play (as Redding recommends) to as much as a couple of turns for the bushing to move around. However, all this seems to do is determine how far down the neck is actually resized with the tighter adjustment not quite getting me to the point of actually touchong the shoulder. I've also tried screwing the main body of the die further into the press so as to increase contact with the shellholder - this also did not seem to help. Nevertheless, I may have been a little timid in how much contact I allowed as I did not want to apply excessive force to the die.

    To further convince myself, I also ran a shell casing through the body die first and then the neck sizer. When I tried to chamber the empty casing it was just as tight as before it had been sized so I'm pretty sure that the problem is that the shoulder is still ending up too far forward. Suggestions and/or clearer explanations would be most welcome.

    What am I doing wrong? Can the neck sizer die be used to bump the shoulder back a couple of thousands? If so, how? What else can I adjust?

    Thanks,
     

    Winchester 69

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    Re: How do you bump shoulder a couple of thou?

    The Redding neck sizer does not bump the shoulder. The body die is used for that purpose. If the body die is contacting the shellholder and you're not pushing the shoulder back far enough, you'll have to do something differently. You're correct in not over-stressing your press. Once solid contact between the shellholder and die is made, more force won't accomplish anything.

    If you need to lower the shoulder of the body die you probably have a tight chamber, whether by design or otherwise. The bottom of the die can be trimmed, but it is a difficult process requiring a machinist, or a return trip to Redding, to achieve, due to the metal being hardened.

    The common method is to shorten the shellholder by lapping it on emery paper. Place the paper on a flat surface, like plate glass, and lap the top of the shellholder in a figure-eight pattern. Using a grinder will result in an uneven surface. The shellholder is also a hardened piece.

    If your rifle has a minimum spec chamber (custom reamed), the diameter of the case body may be interfering with the chamber wall. This situation requires a small-base body die, which Redding supplies in some calibers. The small-base dies accommodate minimum SAAMI spec. Standard dies assume a generous chamber. At any rate, determine where the tightness occurs before buying or changing anything. Marking a fired case with a magic marker and chambering it will show where the interference occurs.
     

    ryder198

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    Re: How do you bump shoulder a couple of thou?

    How do you know how much you are bumping the shoulder? How much is too much?

    I usually screw my die all the way to touch the shell shoulder then back it off a turn or two, but have never been too confident in my ways.

    Good info Winchester.
     

    Rafael

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    Re: How do you bump shoulder a couple of thou?

    I use the Redding Competition Shellholder set to adjust how far
    This is a set that contains shellholders that are .002", .004", .006", .008", and .010" taller than a standard shellholder. This means they touch the bottom of the die sooner than a standard shellholder.

    I bump the shoulder, and quantify the result with a Redding Instant-Indicator or with the Hornady headspace tool set.
    The T-7 lends itself well to the Instant-Indicator since you can just spin the head to move between bumping and measuring.
     

    MitchAlsup

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    Re: How do you bump shoulder a couple of thou?

    I use the RCBS case mic to measure the sholder position.

    I use a body die to push the sholder back. If the body die is not sufficiently down in the press, the sholder will actually lengthen as the body die shrinks the case wall diameter (near the web).

    If you are trying to push the sholder back only and exactly 0.002, then you need to measure before and after to guarentee success. Anything less than 0.002 and the brass will simply spring back (and avoid being sized--and sometimes lengthen).
     

    pell1203

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    Re: How do you bump shoulder a couple of thou?

    Ok guys, based on all of your comments, as well as some additional reading, I may be getting a better handle on what this is all about. Let me try to summarize what I think I'm hearing you all tell me.

    1. Once I shoot the brass several cycles in the same chamber, the brass will have effectively expanded (been fire formed) to fit my chamber.

    2. Next, neck sizing the brass using my Type S - Bushing Neck Sizing Die is only adjusting the neck size back to a dimension that provides proper neck tension during the bullet seating operation.

    3. If and when, the bolt becomes a little harder to open and close, it indicates the brass is no longer as springy and may be getting a little oversized for my chamber. Only way to remedy this is to use the Body Die in my set (only does body sizing and shoulder bump) to bring the case back to specs. With this die, only the body and the shoulder is affected. It will do nothing for the neck tension - I'll still need to use the Type S - Bushing Neck Sizing Die to adjust that. Alternatively, I could use Redding's Type S - Bushing Full Sizing Die as this die allows me to perform the body sizing, shoulder bump, and neck tensioning as an all-in-one operation.

    My original intent was to just bump back the shoulder a bit and leave the remainder of the case at the fire formed dimensions in order to work the brass as little as possible. However, it does not look like I can accomplish this using any of the die set combinations available to me above. In fact, after thinking the problem through, it may not even be desirable as the shoulder bump operation may push the body dimension even further out of spec whenever the case sidewalls are not supported by the body sizing portion of the die.

    Let me know if I've still got something "back asswards."

    In the meantime, I'm going to go try a few adjustments with the body die... Redding Instant Indicator looks interesting.

    Thanks,
     

    Winchester 69

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    Re: How do you bump shoulder a couple of thou?

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pell1203</div><div class="ubbcode-body">My original intent was to just bump back the shoulder a bit and leave the remainder of the case at the fire formed dimensions in order to work the brass as little as possible. However, it does not look like I can accomplish this using any of the die set combinations available to me above. In fact, after thinking the problem through, it may not even be desirable as the shoulder bump operation may push the body dimension even further out of spec whenever the case sidewalls are not supported by the body sizing portion of the die.</div></div>
    I BELIEVE YOU'VE GOT IT!

    Actually, your concerns regarding the dimensions of the case body are the reason for having custom-made dies. You're dealing in extreme accuracy considerations here. Experimentation should tell.

    Another approach would be to try Forster's shoulder bump/neck-sizing die.
     

    craigp40

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    Re: How do you bump shoulder a couple of thou?

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Winchester 69</div><div class="ubbcode-body">The common method is to shorten the shellholder by lapping it on emery paper. Place the paper on a flat surface, like plate glass, and lap the top of the shellholder in a figure-eight pattern. Using a grinder will result in an uneven surface. The shellholder is also a hardened piece. </div></div>

    I had to use this method for my 243AI and it worked fine. Do it a little and take a measurement. No need to take off more than necessary.
     

    Luke

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    Re: How do you bump shoulder a couple of thou?

    Get yourself a quality full length sizing die and a case headspace gage. Screw your sizing die in and leave it a little high. Size a piece of brass and check it in the case gage. Continue to screw down the die until the case sits flush on the case gage between the go and no-go marks. You brass is now correctly sized. Problem solved.

    Yes, I know all the arguments about how full length sizing overworks your brass etc. etc. but seems how you're going to end up full length sizing every 4-6 loadings anyway you might as well just do it every time and save yourself the time, effort, and headache of changing everything around. By full length sizing every time you have just succesfully eliminated 3 or 4 variable in your reloads. Benchrest shooters can afford to neck size only because they are working in pristine conditions and are cleaning their barrels and chambers every string anyway. If you're running a tactical/field rifle you can't afford to work at edge of maximum case tolerances because the second you get a little grit or dirt in your chamber you'll find yourself with stuck case or cases that won't even chamber.

    For more information on this Glen Zediker's book "Reloading for Competition" is an excellent resource.
     

    MitchAlsup

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    Re: How do you bump shoulder a couple of thou?

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pell1203</div><div class="ubbcode-body">My original intent was to just bump back the shoulder a bit and leave the remainder of the case at the fire formed dimensions in order to work the brass as little as possible. However, it does not look like I can accomplish this using any of the die set combinations available to me above. </div></div>

    The case wall must be supported in order to push the sholder back without crushing the case wall during the pushing. That is why the body die sizes the case walls while pushing on the sholder--if it did not you; would not like the outcome.
     

    vinconco

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    Re: How do you bump shoulder a couple of thou?

    I use the Forster bushing / shoulder bump die but instead of using the bushing to resize the neck I use a lee Collet neck sizer and then bump the shoulder in the Forster die when necessary. To get even neck tension using a bushing die you should turn the necks... something I like to avoid in my tact rifles. I use the Stoney Point gauges to measure the shoulder and bump them back around .002 from fired dimension.
     

    Halfnutz

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    Re: How do you bump shoulder a couple of thou?

    All good info above. I have and like the Hornady (stoney point) gages myself. Winchester69 is correct in what he mentioned about taking alittle off the top of your shell holder. A bench stone or sharpening stone that is like new, as in a good flat surface, will work well also in place of or in addition to sandpaper.

    Measure the hieght of the shell holder and then start to work it down. Take a little off then give it a try it in your press. repeat until you get what you want. The Hornady Headspace gage will give you an idea of how far off you are.
     

    johngfoster

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    Re: How do you bump shoulder a couple of thou?

    +1 on the Horndy gauges. At first, I had trouble using them due to the small cratering of my primers (oversized firing pin hole on bolt-face). To overcome this, I just put it in my primer seater and squeeze it down to just below the surface of the case head (like a properly seated primer). Then I can measure without it interfering.
     

    psinclair

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    Re: How do you bump shoulder a couple of thou?

    i bump my shoulders back based on feel. by running the freshly bumped case into the chamber and closing the bolt to see how it feels. just a small amount of adjustment on the body sizer at a time until i get the correct fit. be sure not to over-bump the shoulder causing case seperation just above the web after 1 or 2 firings. brass can and will become work-hardened the more it is fired so as stated above its a good idea to anneal the necks every 4 or 5 firings.
     

    Crazy Dog ll

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    Re: How do you bump shoulder a couple of thou?

    +1 I full sized,next 3 or 4 rounds neck size, shoot til its has troubles chambering, then F/L,fire then neck size next 3 or 4 rounds,but their will come a point and time the shoulders need bumping back and you're ran out of adjustment on youe dies. That's when , the Redding dies with the shell holders,which are made in incerments size,.002,etc come into play. I alway load and chamber the first few rounds that I load off the press,not to end up with abatch of twenty or of "misfits". I think Rafel's method is the correct way to do it. I gey about 10 firing out of the brass before encountering neck splits.
     

    pell1203

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  • Dec 27, 2007
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    Re: How do you bump shoulder a couple of thou?

    As suggested above, I used the body die to bump back the shoulder a little at a time until I could easily close the bolt again. Once on the sweet spot, I locked down the die and ran a couple more previously tight cases through and got all of them to chamber smoothly. Turns out I did not need to take anything off the shell holder as the proper adjustment occurred just as the die very lightly kissed the shell holder.

    For now, I believe I have my original problem solved and better understand the entire process. I'm hoping to get through another 3 to 4 cycles with just neck sizing before having to bump the shoulder back again. Annealing will have to wait for next cycle... don't want to do too much all at once and need time to scrounge up parts to set up the rig to do it.

    Thanks again for all of your suggestions.
     

    vinconco

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    Re: How do you bump shoulder a couple of thou?

    I usually do my (rough) load development using the same case until I get in the velocity / SD range that I need then I go to multiple cases. Having a shooting window on the side of my reloading room helps a lot. In doing this I sometimes shoot the same case as much as 30 times which gives quite a bit of instant feedback on how many times you can fire a case and how often resizing is necessary. What I have found is that usually only a shoulder bump is necessary but after about 20 firings or so a body size becomes increasingly necessary. When I get to the point where I have to body size every other time I scrap the case. I usually use culls for this and save the "good" cases for final load development.
     

    RADcustom

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    Re: How do you bump shoulder a couple of thou?

    I can't imagine a brass knife being good for much.
    smile.gif
     

    pell1203

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  • Dec 27, 2007
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    Re: How do you bump shoulder a couple of thou?

    Winchester... appreciate the link. Already thinking about how to rig something up. Thanks again for your comments.
     

    Winchester 69

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    Re: How do you bump shoulder a couple of thou?

    You're most welcome. Glad they were helpful.

    For annealing, I had considered a Bunsen burner using natural gas. Believe the flame temps are somewhat similar. While the machines are nice, an electric screwdriver (or something similar) is simple. Some have said that the TempiStik doesn't mark well on brass, but it may have something to do with how the brass is cleaned. The TempiLaq leaves a residue. After a little practice, you probably won't need the marker.
     

    myerfire

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    Re: How do you bump shoulder a couple of thou?

    When I first started annealing, I used the Tempilaq several times until I felt confident. I no longer use it.
    myerfire