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Trim Die question

Discussion in 'Handloading and Reloading' started by Bull Nutria, Oct 16, 2011.

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  1. Bull Nutria

    Bull Nutria Member

    Dec 26, 2008
    Houma , LA
    I recently purchased a RCBS 7mm08 trim die. i have a lyman shell holder and adjusted the die flush(read contacting the bottom to the trim die in my Lyman Spartan press. i was trimming cases that were about 2.39 to 2.43 ish. the max case length is 2.035. the trim to length is 2.025.

    my question is that i was having a hard time getting the case to about 2.026 to 2.028.. could this be from the lyman shell holder being too thick??

    I don't have an rcbs shell holders or i would try trimming with a different shell holder.

    What do you think fellas?

  2. cfullgraf

    cfullgraf Member

    Oct 19, 2010
    East TN
    I have read that you are supposed to use dies and shell holders from the same manufacturer because there are small differences in the shell holders' thickness that the manufacturer accounts for.

    Redding sells shell a line of shell holders that come in different thicknesses for adjusting how deep the case goes in a die. So, shell holders of different thickness do make a difference.

    You could take a shell holder and grind off a little to get the case to go deeper into the die.

    I have never worried about using shell holders from the same manufacturer of my dies. I use what combination I have on hand. Frequently, I buy the shell holder I can find as opposed the one I want.

    When I trim cases, I want them the same length but have not worried if they were one or two thousandths longer than the minimum trim length. I do use a trim die for a couple of cartridges.

    Hope this helps.
  3. sugarmaker

    sugarmaker Member

    Jan 24, 2010
    All regular shellholders (Lyman, hornady, RCBS, lee, redding, etc...) have .125" from the base of the shell to the top surface of the shellholder. Most are very good this way, within .001". If your shellholder is touching the die at top stroke and you are really getting that file flat on top of the die, then I would guess the trim to length of the die is a bit long. It's a bit tricky to get the file totally flat on the die top, so its an area to watch. I did this until I got a rotary trimmer - I file no more.

    Also, make sure the die is straight in the press - some allen screw locks can significantly tilt the die.
    Last edited: Oct 16, 2011
  4. beatledog7

    beatledog7 Member

    Jun 18, 2011
    Could be that your press cams over on the top of the ram stroke. If this is the case, when the handle is all the way down, the ram has actually dropped a few 1000ths, and that would be throwing your length off. Get your eyeball down at the level of the top of the ram and slowly cycle the handle through the last 10% of the stroke, and watch the top of the ram to see if this is the case. It is with my Hornady LNL, and it means I have to sometimes adjust the die height to account for the cam over distance.
  5. ranger335v

    ranger335v Member

    Dec 3, 2006
    To be real, getting within a couple thou of any case length is as precise as it needs to be.
  6. fguffey

    fguffey Member

    Aug 28, 2008
    Bull N. My favorite trim/forming die is the 308 W, if I had one trim/form die it would the 308 W die.

    The trim/form die is not a finish die meaning after using the trim/form die the case must be sized with the full length sizer die. I will assume you sized the case first then used the trim die. As to trimming to length, I use the 308 W trim die to form/trim 7.7 Japanese when forming 7.7 using 30/06 cases, for those that can keep up that is a large gap between the shell holder and bottom of the die (.312, starting with +.010 to allow for chamber length).

    The trim die must be adjusted to .000, that would be adjusting the die down to remove all the slack in the press, threads and linkage to get consistent results. If I had the chance to start over I would have a trim/form die for every chamber I load for, again the 308 W trim die fills in gaps for trim dies I do not have.

    Again, to avoid moving the shoulder back more than necessary the reloader should know the length of the chamber, again (reminder) the form/trim die is not a finish die, after forming a case the case must be sized in a full length sizer die, and no, the case may not require full length sizing if the reloader knows the length of the chamber from the bolt face to the shoulder of the chamber.

    Mix and match: there are differences in shell holders by design, the Herter's shell holder has an advantage over modern? shell holders, wasted on modern reloaders, the deck height is .125, measuring the deck height of a shell holder can be accomplished with a dial caliper. The difference between Lee and RCBS, the lee has a loose fit, again, that does not mean anything to most, for me it allows for sizing cases an additional .003 thousands for short chambers.

    F. Guffey
  7. jerkface11

    jerkface11 Member

    Oct 27, 2005
    As long as they all come out the same length you shouldn't worry about it.
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