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how does one "bump back the shoulder" on a case

Discussion in 'Handloading and Reloading' started by RevolverMan567, Jun 23, 2008.

  1. RevolverMan567

    RevolverMan567 Well-Known Member

    My grand pa game me a custom 270 he has had fr years, gun is shooting his remaining handloads like crazy so i decided to cook up some of mine. Well i full length sized, measured eveything chamfered, loaded and went to chamber one before i reloaded the rest(whew)

    went in ok, but the chambr is Tight. well i finally got the bolt to close and the shoulder is chewed up and i think it need to be bumped back. COL is slightly shorter than reccomended and the bullet isnt touching the lands.

    how do I adjust my die to bump back the shoulder? Do i just screw the FL sizer in all the way or what?

    thanks in advance.
  2. strat81

    strat81 Well-Known Member

    Yes, try screwing the die in further (i.e., towards the shellholder). The die instructions should help.
  3. nicholst55

    nicholst55 Well-Known Member

    You can also do this by purchasing a Body die from Redding. It does not size either the case neck or body(despite its name), and only touches the case shoulder. Benchrest shooters typically are about the only people who use them.

    If I were going to be loading for just the one rifle, I'd simply adjust my sizing die so my brass fits that specific chamber.
  4. 243winxb

    243winxb Well-Known Member

  5. LB7_Driver

    LB7_Driver Well-Known Member

    - If the shoulder of the case is chewed up after chambering the round, then something is wrong with the chamber. Have it checked!
    There should be no chewing!
    Chewing is bad!
    Chewing is a clear warning sign!
    Do not ignore the warning signs of chewed up brass!

    Now that we're clear about that -

    OK, on to the rest..
    A full length size die is designed to be turned down so it contacts the case holder when the ram is at full extension... and maybe just a tad more so it cams over slightly. Adjusted like this, the cases will be sized to fit a minimum-spec chamber. Most chambers are slightly larger than min-spec.

    Technically, the process of "bumping" a shoulder does not size any other part of the case... it just pushes the shoulder back a few thousandths, and requires a special "bump die". Redding has sold these for many years even though they have not been listed in their catalog.

    Most people bump the shoulder with a full-length die, which works very well by almost everyone's standards. There are a few die-hard benchrest shooters who insist on using a dedicated bump die to bump the shoulder.

    If the cases need to be bumped, then they are also probably close to needing annealing. Many people scrap the cases at this point to avoid the work and a possible failed case.
  6. steve4102

    steve4102 Well-Known Member

    Chewed up necks?? Did you trim your brass. You said you "Measured everything", what was the length of your brass? Do you have a reloading manual? If not you should get one or 10, they are a must.
  7. RevolverMan567

    RevolverMan567 Well-Known Member

    let me be a little more clear

    i said chewed up because i was pissed off after messing with it for so long and i exaggerated it, after the brass was lubed and sized it was nice and shiny when i went to chamber it there was resistance camming the bolt handle down. aftr it finally went the neck looked fine, no marring, but the shoulder has light scraping marks in a ring around the neck, no doubt from where it was in tight contact with the chamber at the shoulder and tisted when the bolt handle was cammed down.
  8. redneck2

    redneck2 Well-Known Member

    Do you have any idea how many times each case has been loaded? How hot?

    Wondering if you're getting brass flowing to the front of the case thickening the necks. You can use a sharpie or soot the necks and cases to see exactly where they're rubbing.

    Just something else to check.
  9. 243winxb

    243winxb Well-Known Member

    Could the chamber be dirty? I would use a 45cal. brass brush to clean that area of the chamber to see if it helps. I though at first your dies needed cleaning in the same way, but you said after sizing the brass looked fine.
  10. Walkalong

    Walkalong Moderator

    Use your full length die to "bump" your shoulder back. The other posters are right, technically you are not just bumping the shoulder, but you want to size the body a bit anyway. It will keep you out of trouble with work hardened brass that will no longer chamber.

    If you know how to take the fireing pin/spring assembly out of your bolt you can easily get the sizer set right for your chamber. Adjust the sizer die so it just barely, or even not at all, sizes the brass. Then chmber the brass and close the bolt, sans the guts, and see if it will close. It should not yet. Then keep adjusting the sizer down a bit at a time until it will. That is the best for your chamber. You will be sizing the brass enough to chamber, but not any more than needed. It will extend brass life, and can be more accurate.
  11. USSR

    USSR Well-Known Member



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