Setting up a Full Length die.

Discussion in 'Reloading' started by AJ Peacock, Aug 10, 2009.

  1. AJ Peacock

    AJ Peacock Well-Known Member

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    I've noticed several posts recently that were related to setting up a FL (full length) resizing die. I decided to document how I setup a full length die. If I've missed any steps or failed to fully explain something, please let me know and I'll update this post.

    Incorrectly setting up a sizing die can result in too much headspace (slop in the chamber) and will usually result in poor accuracy, short brass life and in extreme cases can lead to case head seperation.

    If you are setting up a new die, it should be thoroughly cleaned. Automotive brake cleaner works well for this (do this outside, as the fumes are not good for you). Use some Hoppes afterwards and then swab it out as clean as possible.

    Here is a die that is dis-assembled and ready for cleaning. Once it's clean, do not reassemble (leave the decapping assembly out of the die).

    [​IMG]

    Leave the decaping pin out of the die during the first stage of die setup. We will use the decapping pin to remove the spent primers.
    Here I've decapped the spent primer by tapping it out over a small hole in the 2x6 on the bench. It is a good idea to remove the primer prior to measurement, because if the primer protrudes at all below the head of the brass, it will affect your measurements.

    [​IMG]

    Here is an example of a primer that has flowed back into the firing pin hole. This was caused by a firing pin hole that is too big, not by a load that was too hot.

    [​IMG]

    What is needed to correctly setup a die is some method of measuring your brass. I use a Caliper and the Hornady headspace gauges (shown below).
    There are other purpose built tools (like the tool from Larry Willis, that does a great job of this as well).

    Here I'm measuring a new piece of brass. I zeroed the caliper on the new brass, so we can see how much headspace MY RIFLE has with this batch of new Norma brass.

    [​IMG]

    The first step is to find what the once fired length is. You'll want to use once fired brass, since it will have expanded to fit the chamber and then will have 'sprung back' a little.

    [​IMG]

    If you use brass that's been reloaded several times, it will not have sprung back and your measurement will be a bit longer. Your measurement will also be subject to how many times the brass has been fired.
    Subsequently, I use once fired to eliminate that variable. In this example, the once fired brass measures .0045" longer than the new brass. If my once fired brass will chamber in my rifle without ANY tightness, I will attempt to resize my brass to match this number.

    Once fired brass will typically spring back about .001", so matching this number will give me about .001" clearance with all my reloads.
    If the Once fired brass feels tight when chambered, then I will subtract .001" from it's measurement and that will be the length I will use when adjusting the die. For this example, I'll set the resizing die to push the shoulder back to .0035" (or as close as I can make it).

    After lubricating the once fired brass with some Imperial sizing wax, I resized it with the die about a quarter inch from the shellholder. I measured it and it hadn't moved the shoulder at all. I repeated this step by screwing the die in about 1/10 of a turn at a time until I achieve the 'bump' I am looking for.

    Here is the resized brass.

    [​IMG]


    Continued on next post, to get the final 2 images into post. ...
     
    Last edited: Aug 10, 2009
  2. AJ Peacock

    AJ Peacock Well-Known Member

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    Here is a closeup of the shellholder to die clearance after adjustment.

    [​IMG]

    Notice that the shellholder DOES NOT touch the bottom of the die. Your die instructions will probably tell you to adjust the die until it touches the shell holder, but this will usually result in pushing the shoulders back too far. Your die might be further or closer to the shellholder than this, but it will be adjusted correctly for your rifle.

    Put your die back together and lock it down, so you won't have to re-adjust it later.

    When you put the decapping assembly back in, adjust it so the tip of the decapping pin protrudes just below the shellholder. This will let it fully remove the spent primer.

    [​IMG]

    In this example, I'm using a full length sizing die that uses neck bushings. I adjust the bushing stop to allow a very slight movement of the neck bushing.


    Hope this helps someone,
    AJ
     
    Last edited: Aug 11, 2009

  3. Joel Russo

    Joel Russo Official LRH Sponsor

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    Very well put A J.lightbulb
     
  4. alf

    alf Well-Known Member

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    Great post. A picture tells a thousand words.

    Just wanted to add that for freshly annealed brass, the setting on your die is mucho less than for work hardened brass, due to spring back, or lack there of on old brass.
     
  5. SQ Stalker

    SQ Stalker Active Member

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    Great post. I adjusted mine in a similar manor per the instructions w/ a RCBS Precision mic for headspace. I've been able to get more consistance headspace from the die than from the chamber.

    I find the part about the brass w/ more reloads having a different spring back very helpful. I've been wondering what was goin on. My measurements were drifting as the brass was reloaded and fired more times. That makes since.

    Stalker
     
  6. AJ Peacock

    AJ Peacock Well-Known Member

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    One reason to keep brass together that has the same number of reloads is the springback issue. You'll find you may need to adjust the die down further to get the same shoulder bump with brass that has been reloaded a number of times than with once fired brass.

    AJ
     
    Last edited: Aug 10, 2009
  7. woods

    woods Well-Known Member

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    Great pics!

    Well I ran into this in American Rifleman May 2009 issue, article on Smith & Wesson's 460XVR on page 54

    --------------------------------------------------------------------------------------------------------------------------
    quote:
    Had Hornady's engineers not had prior experience loading the .454 Casull, the 460 S&W Mag.'s case would have presented another dilemma. With pressures similar to those of the .454 Casull and production-type revolvers using the new cartridge, Mittelstaedt determined the cases needed to be "cold worked" to the brass' limits, which resulted in maximum strength/hardness, as well as better "springback". Spring back is the case's ability to, under high pressure, expand to the size of the chamber then retract enough for easy extraction. "Soft" brass doesn't "spring back", making extraction difficult.
    ---------------------------------------------------------------------------------------------------------------------------

    It always seemed to me that new brass had more springback. That was observing the behavior of the brass in my dies. I went through it on this thread

    Springback - Topic Powered by Eve For Enterprise

    I'm not sure if this is what you're saying here

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    If you use brass that's been reloaded several times, it will not have sprung back and your measurement will be a bit longer. Your measurement will also be subject to how many times the brass has been fired.
    Subsequently, I use once fired to eliminate that variable. In this example, the once fired brass measures .0045" longer than the new brass. If my once fired brass will chamber in my rifle without ANY tightness, I will attempt to resize my brass to match this number.

    Once fired brass will typically spring back about .001", so matching this number will give me about .001" clearance with all my reloads.
    If the Once fired brass feels tight when chambered, then I will subtract .001" from it's measurement and that will be the length I will use when adjusting the die. For this example, I'll set the resizing die to push the shoulder back to .0035" (or as close as I can make it).
    ---------------------------------------------------------------------------------------------------------------------------
     
  8. LRHWAL

    LRHWAL Well-Known Member

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    Great post AJ.

    I would add that in my experience as you lower the sizing die the head space can initially INCREASE as the body of the case is sized down and as the brass goes somewhere it lengthens the headspace (whilst you aren't bumping the shoulder yet). As you then screw the die in deeper it will decrease headspace again.

    I found this really disconcerting when I first got a headspace gauge and measured for the first time.

    I hope I'm explaining this well enough.

    I suspect if your chamber is tighter this is less of an issue.
     
  9. AJ Peacock

    AJ Peacock Well-Known Member

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    LRHWAL,

    You are exactly right, I was going to mention that but decided to leave out some of the details and have them discussed here. I haven't seen it happen so much with my WSM or RUM based cartridges, it may have something to do with the taper (or lack of taper) of the cartridge; I'm sure you are right and it is related to the comparative size of the die and the chamber as well.

    AJ
     
  10. Winchester 69

    Winchester 69 Well-Known Member

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    Visualizing what LHRWAL is saying, is the brass' body not initially lengthening, and subsequently shortening as the case shoulder is engaged? If this is so, then the headspace is acting oppositely in dimension, actually decreasing initially and then increasing. I'm not refuting what is proposed, just asking if its being stated correctly.
     
  11. AJ Peacock

    AJ Peacock Well-Known Member

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    Woods,

    Yep, It has always seemed to me that new brass had more spring back. Brass that has been used a lot tended to measure longer and require more resizing.

    At first reading, I didn't agree with the Hornady engineers, but after some consideration, I think I do. It makes sense that as a metal gets work hardened, it tends to be more resistant to being deformed (more than when it was softer). I am certain that brass that has been shot multiple times are harder to resize. I'm also certain that once fired brass is smaller (headspace wise) than brass shot multiple times. It may be that we are trying to compare apples and oranges, and that we are using the term 'spring back' inappropriately.

    If you think about shooting/resizing/shooting/resizing as a process, a cartridge will actually grow in diameter a little each cycle (because we don't have an easy method for sizing the diameter more as the brass becomes harder). We can push the shoulder back more as the brass gets harder, but we can't adjust the diameter of our dies (collet/mandrel dies excepted).

    So to be correct, work hardened brass has more 'spring back', but once fired brass ends up smaller than the chamber (as compared to brass fired multiple times) because it's only been through one cycle of firing/resizing.

    If you fire the same brass a half dozen times, it will pretty closely represent your chamber dimensions. New brass hasn't been processed enough times to move from it's orignal size to the chamber dimensions yet. It's tough to compare the forces involved in firing a cartridge (lots of pressure and heat) and the forces involved in resizing a piece of brass (not much pressure and almost no heat).

    I read the thread you referenced and one thing intrigued me. One of the posters said that a piece of brass that is resized will grow over time (without being fired) and will behave differently whether it had been annealed or not. I went down and measured some reloads and once fired brass that has been sitting since 7/2007 and the measurements have not changed (lucky that I had documented the dimensions of the once fired and reloaded cartridges!).

    OK, enough rambling.

    AJ
     
    Last edited: Aug 11, 2009
  12. AJ Peacock

    AJ Peacock Well-Known Member

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    As the case body is sized, the case length will actually increase (decreasing the headspace inside a chamber). Once the shoulder is engaged, then the case length is shortened (increasing the headspace in relation to the chamber).

    I think everyone is saying the same thing, just in different ways.

    AJ
     
  13. LRHWAL

    LRHWAL Well-Known Member

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    "Visualizing what LHRWAL is saying, is the brass' body not initially lengthening, and subsequently shortening as the case shoulder is engaged?" Yes and "As the case body is sized, the case length will actually increase (decreasing the headspace inside a chamber). Once the shoulder is engaged, then the case length is shortened (increasing the headspace in relation to the chamber)." Yes again...

    I was on increasing case headspace and yes, decreasing chamber headspace. To my credit I asked if I was explaining it well :D
     
  14. woods

    woods Well-Known Member

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    Here's a question but first let me set it up. As discussed when you set your die so that it has started resizing the case body, it starts pushing the shoulder forward. On once fired cases the shoulder is typically a few thousandths away from contacting the chamber shoulder.

    Question

    In your experience, when sizing once fired brass, is it possible to push the case shoulder far enough forward to contact the chamber shoulder?

    Last time I checked, I was only able to push the shoulder .001" or so on once fired cases and that was not enough to enable the body die to contact the shoulder and place it exactly where I wanted it. Is there any other way to accelerate the brass expansion sequence so that you can size for a slight crush fit on once fired cases?