Polishing a body die?

Discussion in 'Reloading' started by jsthntn247, Aug 8, 2013.

  1. jsthntn247

    jsthntn247 Well-Known Member

    Messages:
    659
    Joined:
    Jan 14, 2009
    Anybody ever polish a body die when it's sizing too much? My redding body die is sizing my cases .0035 smaller in diameter than fired. I considered polishing it out with 600 grit wet dry paper until I get .001 smaller than fired diameter. Sound doable?
     
  2. Bullet bumper

    Bullet bumper Well-Known Member

    Messages:
    1,035
    Joined:
    May 20, 2009
    You don't have to push the case in all the way every time with a body die when a shoulder bump is not required .
    Fired case size varies from and easy fit to a sticky hard to chamber case.
    So be careful what size case you choose to adustt the die to.
    Some cases will spring back .001 coming out of a size die anyway .
    .001 critical match could be a bit close when changing brass brands and different batches .
    You may have a small base body die and not need one . However I would just try not pushing the case in so far each time and only shoudler bump when needed. Keep lubricant film as thin as possible and keep the die and cases very clean.
     

  3. J E Custom

    J E Custom Well-Known Member

    Messages:
    7,266
    Joined:
    Jul 29, 2004
    Back off the die just a little until you get the fit you want Just like Bullet Bumper said.

    First take the expander ball out so you don,t over work the case (One is all you need to use for this)
    then size the fired brass and check it in the chamber. Keep turning the die down until you get the size/fit you want. Then lock the die in position, remove it from the press and re-install the expander
    ball. You should be ready to load now. when you look at the case you may have a very small area of the neck that has not been sized, That's OK.

    There is nothing wrong with your dies so don't polish or grind on them.

    J E CUSTOM
     
  4. jsthntn247

    jsthntn247 Well-Known Member

    Messages:
    659
    Joined:
    Jan 14, 2009
    I am running the brass up in the case far enough to get a .001 shoulder bump so it feeds easily in a match. Any more and I get to excessive of a bump and any less I get no bump at all. This die doesn't have an expander, it's strictly a body die. This die is squeezing the cases down .004 when .001 is all that's needed to chamber properly. This excessive squeezing is working the brass 4x more than needed and leading to shorter brass life. I guess the only way to fix it is custom dies made from a fired piece of brass. I have my own reamer so each chamber from now on should be identicle and maybe justify the added cost of the die.
     
  5. Bullet bumper

    Bullet bumper Well-Known Member

    Messages:
    1,035
    Joined:
    May 20, 2009
    If you have to lapp the die . This is how I would do it.
    Machine up a mandrel that fits the neck part of the die neat but with an easy slide fit. Make it long enough to stick out both ends of the die about 2.5 inches.
    Gaul up a section of the mandrel that will be inside the die . Machine up a base plug with a pouring hole to one side that centers the shaft in the base of the die then pour molten hard lead alloy into the die so it hardens around the shaft .
    push it out when cold. Cut away any part of the lead lapp that you don't want to contact the die such as the shoulder and any sprue in the neck area . Put one end in an electric drill and load up the lead with cutting compound. Lube up the upper part of the shaft and insert it so the upper part of the shaft sticks out the top of the die and runs on centre inside the neck area of the die. Have at it for a while and reload the lapp with cutting compound as required . Have a measure every time you reload the lapp to get any idea of how much is being removed at a time. Re melt and recast the lapp when it gets loose and stops cutting . This way you have a chance of keeping it round as you go.
     
  6. Bart B

    Bart B Well-Known Member

    Messages:
    2,483
    Joined:
    Dec 25, 2005
    I don't think sizing fired case bodys 3/1000ths smaller in diameter is gonna cause any problems. A test with a Federal brass .308 Win. case full length sizing it down that much and setting the shoulder back a thousandth worked fine for 47 reloads on the same case with max loads. My 30 caliber magnum cases are full length sized that much and nary an issue whatsoever.

    Bottleneck cases headspacing on their shoulders center perfectly in the chamber up front where it counts when fired regardless of how much clearance there is around the case. Their back end's pushed against the chamber wall by the extractor; this happens with virtually all chambered rounds anyway.

    One could lap their die out a bit so cases aren't sized down too much, but I think it would take a rifle and ammo and marksman that shoots no worse than 2/10ths inch at a hundred to tell any difference.
     
  7. jsthntn247

    jsthntn247 Well-Known Member

    Messages:
    659
    Joined:
    Jan 14, 2009
    Bart the reason I'm wondering this is because I'm having to trim my brass so much after each firing. Trimmed brass measures 2.007 after firing it is 2.017. It's growing 10 thou with only bumping .001?? I'm concerned about short brass life with that much growth on each firing.
     
  8. Bart B

    Bart B Well-Known Member

    Messages:
    2,483
    Joined:
    Dec 25, 2005
    Every .308 Win case I've fired has been shorter (head to mouth) by about .003" after firing. But they do lengthen almost .004" after full length sizing bumping the shoulder back about .002"; they grow near .001" each time. This is with standard SAAMI spec chambers and across 6 different full length sizing dies.

    Both my 30 caliber magnums did the same thing except about .001" more, probably due to a bigger case.

    So, I think you rifle chamber may be a bit on the big size. Is it a factory chamber?

    What cartridge is this happening with?
     
  9. jsthntn247

    jsthntn247 Well-Known Member

    Messages:
    659
    Joined:
    Jan 14, 2009
    It's a 308. Load is 45.4 Varget, Lc LR brass, 155 sierra palma bullets. It's a match gun chambered with 95 palma reamer. I anneal after each firing.
     
  10. larrywillis

    larrywillis Well-Known Member

    Messages:
    192
    Joined:
    Mar 18, 2002
    Don't worry your cases that need trimming. It's perfectly normal for 50,000 PSI to stretch your brass. Just trim your cases to the recommended Trim to Length, and make sure your handloads have about - .001" clearance at the shoulder.

    Adjust your die height accurately, and the case diameter will be fine.
     
  11. jsthntn247

    jsthntn247 Well-Known Member

    Messages:
    659
    Joined:
    Jan 14, 2009
    Thanks Larry. Your collet dies work well on my magnums also.
     
  12. larrywillis

    larrywillis Well-Known Member

    Messages:
    192
    Joined:
    Mar 18, 2002
    jsthntn247 .........

    One exception to my last post is when reloading belted magnum calibers. After a few reloadings, the brass above the web gets thin enough to bulge. If the brass is allowed to get too thin it will crack and separate the head.
     
  13. Bart B

    Bart B Well-Known Member

    Messages:
    2,483
    Joined:
    Dec 25, 2005
    when fired?
     
  14. larrywillis

    larrywillis Well-Known Member

    Messages:
    192
    Joined:
    Mar 18, 2002
    Barb B ..........

    ??? I'm not sure what you mean.

    I was referring to what happens when a case is fired. The stretching of your overall case length is normal as brass migrates forward from chamber pressure.

    Excessive case stretching is avoidable by minimizing the shoulder clearance that your handloads have in your chamber.