How to bump the shoulder???

Discussion in 'Reloading' started by OKbow87, Nov 3, 2007.

  1. OKbow87

    OKbow87 Well-Known Member

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    I hear alot of guys talking about only neck sizing and bumping the shoulder back... say .002". I am familiar with neck sizing but have always just full length resized when the cases seemed to have a little resistance chambering. I was just wondering if somebody could explain the process of bumping the shoulder back. I was also wondering if it will help with brass life by working the brass less. Thanx guys.

    Colin
     
  2. jes10x1

    jes10x1 Member

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    Shoulder bumping

    If I full length resize, I try to be very careful to bump the shoulder back only a .001 or 2. A friend of mine didn't check & wound up with several separated 223 cases. The problem stopped when he reduced the amount of headspace for the rounds. The old Stoney Point (now Hornady?) or Sinclair int'l tools are great for this job: to custom fit both headspace and bullet depth to a particular rifle.

    Forster Products now makes a bushing die to size necks AND bump the shoulder at the same time without touching the case body walls. You might want to look into that. Drop a note or send a ph # if you'd like to discuss more. J
     

  3. Roll-Yur-Own

    Roll-Yur-Own Well-Known Member

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    When you full length resize you set (bump) the shoulder back. However, it is usually too much. When guys are talking about "bumping he shoulder back 2 thousands", for example, they are using the FL die but not completely resizing the brass.

    What a lot of guys do is rezise a minimal amount and chamber the case, resize a little more, chamber, etc until the case just chambers. That is also known as partial FL resizing. The best way to do it is to buy a set of redding competition shellholders which are a 5 shellholder set with each holder being .002 bigger. What you would do is start with the biggest and work your way down until your brass just chambers. Now you know exactly how much shoulder bump you did.

    I mentioned that the are using a fl die, however they could be using a body die and neck sizing also.

    Also, if you are shooting deer & elk at closer ranges this may not be needed.

    YMMV
     
  4. Varmint Hunter

    Varmint Hunter Well-Known Member

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    It's really very easy. Using an Overall length gauge (I use the Stoney Point but there are others) measure the base-to-shoulder distance on a once fired case. The tool will measure to a point on the shoulder known as the datum line.

    Once you have this measurement you can adjust your FL die down far enough to shorten this length by .001" or .002", as measured on the same gauge. Start with the die backed out a bit and slowly work your way down by sizing-measuring-adjusting (repeat-repeat-repeat) until you get the shoulders to the point that you want.
     
  5. Roll-Yur-Own

    Roll-Yur-Own Well-Known Member

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    Varmint Hunter is right on, but using the competition shellholders eliminated the need to keep adjusting the die.
     
  6. AJ Peacock

    AJ Peacock Well-Known Member

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    +1 Varmint Hunter and Roll Ur Own.

    Exactly correct. In my loading book for one of my rifles I have written.

    "Adjust FL die to touch +10 shellholder, then use +8 shellholder to size .001" under chamber".

    I can setup that die in 10 seconds and be perfect the first time using the competition shellholders.


    AJ
     
  7. CatShooter

    CatShooter Well-Known Member

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    You need to remember that Redding +0.0X" shell holders are not always the answer.

    Because all chambers have +/- tolerances, and all sizing dies have +/- tolerances, you can have (and I have had) a situation where the headspace in a die is longer than the headspace of the chamber.

    So when the case gets tight to chamber, you cannot "bump" the shoulder, because when you put the case into the die, the shoulder of the case does not touch the shoulder of die, so you cannot set it back.

    In this situation, you must modify shell holders to have a "minus 0.0X" length. The standard shell holder has a standing hight of 0.125" +/- 0.001", and these are held to tight tolerances... but you may have to take 10 thou or more off of the top of the shell holder to be able to bump the shoulder back 0.001", if your chamber is shorter than the bump die's headspace.

    I have a set of shell holders that are shortened by lapping on a plate with #800 carbide paper. Each one was made for a specific rifle, and specific die, to exactly match the chamber.

    I have one shell holder that had to be taken down 0.023", before the die would touch the shoulder of the case.

    The point of this is that there are no automatic solutions to the "bump" issue.



    .
     
  8. Winchester 69

    Winchester 69 Well-Known Member

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    Thanks for describing your method. I have heard other methods described that gave what I would describe as less than desirable results, and too many tales of attempts at extreme camming over, trying to achieve the impossible.

    Do you find that it is desirable to use one brand of shellholder over another? Redding advertises their shellholders as being hardened. In your experience, are they the only ones, or are other brands hardened ? I can see the virtue in modifying an unhardened piece, both in ease of processing and in the results.
     
  9. CatShooter

    CatShooter Well-Known Member

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    Double tap :(
     
    Last edited: Nov 4, 2007
  10. CatShooter

    CatShooter Well-Known Member

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    "Extreme camming over" cannot work - it is silly - it would require that you can compress the steel in the die body, which you cannot.
    All you do when you "over cam" is to stress and stretch the frame of the press.

    I use RCBS shell holders (though I am not an RCBS fan)... because when I was a dealer, I wound up with a million of them. They are Okie dokie - Redding shell holders are very good, and the Bonanza shell holders (before they were bought up by Forster) are great!

    All of the above shell holders are hardened. I don't know about LEE (yuck!).

    You take a piece of #800 Silly cone carbide "Wet n dry" paper, and put it on a plate of glass - oil it, and put the shell holder on it and start going in a figure "8" on the paper. Rotate the shell holder in your fingers by 90° every minute, so you won't lap a slope in the shell holder.

    You can do it by trial and error - you will take down about 1 thou a minute (at least I did). Lap down the shell holder a little, wipe off the black stuff, and try a case in the die, then the rifle... do this every minute or two until the bolt closes on the case the way you like.

    Make sure to mark the shell holder with a red "sharpie" pen or something... or put it in a zip lock bag so it doesn't get mixed in with the other shell holders.

    23 thou was the most I have ever had to do - the rest were 6 to 12 thou.

    .
     
  11. kraky

    kraky Well-Known Member

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    If you are getting into reloading and enjoy it please do yourself a favor and get the stoney point (now hornady I guess) headspace bushing kit. You don't need the redding shellholders at all....save your money and put it towards the stoney point kit. (I have them and pretty much use them only because I have confidence they hold a tight tolerance and might help keep runnout down.....not for flexibility of headspacing). If you want to be able to play with headspacing and not move the lock ring sinclair offers a shim kit that is really handy called "skips shims" and you can shim from .002" to .020" easily.

    I always get a kick when people say that just bumping the shoulder is "partial sizing" when it really just plain is correct sizing as you are talking about the final .010-.020" of case travel into the die.....I guess if oversizing your brass is called "full length sizing" then no one should ever do that.
    One last trick in measuring the case for headspace with the bushing kit...always knock the primer out first as you can get .001-.002" protrusion after firing..sometimes slightly more on non belted cases.
     
    Last edited: Nov 5, 2007
  12. Winchester 69

    Winchester 69 Well-Known Member

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    Catshooter

    Thank you very much for expanding on your technique.
     
  13. TGVet

    TGVet Member

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    Bumping and testing.

    It would be fantastic if there were a video or even a very well illustrated short document describing/showing the 2 or 3 different methods of bumping as have been described in the threads. I have read and tried some info via a long time reloader and now bullet maker with his given procedures. Bump til you get your bolt close feel like cutting through butter.. eg; some resistance. Check cases for pressure signs etc.. Took a while and some correspondence and reading etc.. But for those never having done it, or having some comprehension difficulty, nothing beets OJT via a good video or well illustrated document.. Reloading for less than MOA accurracy is fun when you can get even off the shelf rifles to MOA, let alone custom made rigs. The task is not to be taken lightly and comprehension of what one is doing is extremely important.
     
  14. Tim T

    Tim T New Member

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    Redding makes a body die exactly for this purpose. Body dies are designed to full length size the case body and bump the shoulder position for proper chambering without disturbing the case neck. They are made without internal parts and intended for use only to resize cases which have become increasingly difficult to chamber after repeated firing and neck sizing. Midway sells them for about $25.00. They work very well