How do you adjust a body die to just bump the shoulder?

Discussion in 'Reloading' started by encoreguy, May 14, 2008.

  1. encoreguy

    encoreguy Well-Known Member

    Sep 24, 2006
    I am new to reloading and I want to use a body die to just bump the shoulder and use my lee collet dies for the neck. How do I adjust a body die to just bump the shoulder and leave the rest of the fire formed case alone?
  2. boomtube

    boomtube Well-Known Member

    Oct 8, 2007
    You need to adjust the die down until your bolt just closes on the sized case without force or slop. Two ways to do it; use the rifle itself as a gage or use a gage made to measure the case.

    Adusting our 14 threads per inch dies can be difficult because a seemingly tiny change makes a LARGE difference. Most rifle head space tolerances run about 10 thousanths, max to min. A 1/16 turn makes a change of about 9 thousants! This HAS to be done slowly and carefully.

    Using the rifle as a gage, simply back the size die out from shell holder contact about a quarter turn and size a case. Try to chamber it. It probably won't chamber easily (if it does back the die out another quarter turn and try again with another case). Assuming it is too tight, turn the die down another 1/16 turn and try chambering again. Keep this up until the case chambers easily and then back the die out 1/32 th of a turn and try it with another case. Continue back and forth, with fresh cases, until you get the fit you want. Lock the die ring to allow you to return to this precise setting easily.

    Case gages such as the RCBS Precision Case Mic, Sinclair's case measureing tool, or the Hornady/Stoney Point case tools all work well. You can simply measure the case length from head to shoulder. Then adjust the size die to either match the fired case length or a thousanth or two less, as you wish. (The lengths won't ever be completly consistant, the brass in each case will spring back a little differently, so settle for a good average.)

    After the sized body and shoulder are where you want them, the Lee Collet Die will get you some very straight necks!

    Good luck!
    Last edited: May 14, 2008

  3. archdlx

    archdlx Well-Known Member

    Nov 26, 2007
    Good question encoreguy, Thanks for asking it!

    great description, best I've seen.

    Thank you both,
  4. steve4102

    steve4102 Well-Known Member

    Mar 13, 2005
    If you are using a Redding Body Die then you can't. As boomtube described the body die can be adjusted to bump the shoulder back ever so slightly, but the body die also comes in contact with the case body and it will size the case body also. You can't get around it. If you start reforming the case the brass needs to go somewhere. If the Body Die did not make contact with the case body then bumping the shoulder back would also blow the sides out. Go for, you'll be fine. The Collet die and Body die are a great combo.
  5. JeffVN

    JeffVN Well-Known Member

    Mar 19, 2004
    +1 with a Redding body die, even the bushing body die, you can't do it without also modifying teh body at least a touch.

    I haven't seen it mentioned here yet, but I think the best way is to use a piece of fired brass from that rifle (this of course assumes that you can load or buy loaded ammo for the rifle), then start the process discussed above using one of the guages (I use the RCBS Precision Mic) The precision mic and get an average from about 5 or 6 pieces of fired brass. That will give you the measurement of the fired brass then you set up the die to push that shoulder back 0.001-0.002.

    I end up using at least 5 pieces of fired brass for the process, but the tweaking of the die takes a bit of trial and error. Once you got you got it for that rifle.