Resizing Belted Magnums

Discussion in 'Reloading' started by guns_and_labs, Aug 9, 2009.

  1. guns_and_labs

    guns_and_labs Well-Known Member

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    I understand that it is preferable to full-length-resize casings for proper chambering in hunting rifles, but I have a couple of questions:

    1. When I run the fired case through the full length resizing die, I can see marks on the case where it has been resized -- EXCEPT FOR THE LAST .06" BEFORE THE BELT, which remains smooth and untouched. I've tried setting up the die touching the bottom, and even tightened 1/4 or 1/2 turn beyond, but it doesn't seem to matter. Is this a problem?

    I have a collet resizing die on order, but I was wondering if I need to worry in the meantime.

    2. I use a SAAMI-sized chamber check to verify after resizing. Is that sufficient, or do I need to chamber check in the actual rifle?
     
  2. AJ Peacock

    AJ Peacock Well-Known Member

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    Don't worry about resizing it all, as long as it will chamber easily in your rifle, you have resized enough. You are likely 'over-resizing' your brass though. Are you measureing the amount you are pushing your shoulder back? Even though you are reloading a belted magnum, you'll get better accuracy and much better brass life if you headspace off the shoulder instead of the belt. This will make reloading for your belted magnum exactly the same as reloading for a non-belted cartridge.

    All that you need to do is push the shoulder back .001". Your cartridge will chamber easily and you will get the best accuracy and brass life possible.

    If you don't have the equipment to measure your brass, look here Bullet Comparators

    I use the Hornady set.

    Also, what lubricant are you using? I've found the Imperial sizing wax to be the best for bottleneck cartridge resizing.

    Hope this helps,
    AJ
     

  3. guns_and_labs

    guns_and_labs Well-Known Member

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    I have a set of Stony Point (now Hornady) comparators. I'm using the .35 sleeve, though my loading manual indicates the neck should be .34.

    Right now my fired brass measures 2.360 to the top of the shoulder, and it's resizing to 2.346. Obviously more than .001, but how do I adjust the sizing die to bump less?

    I'm using Imperial Application Medium on the neck, and Imperial Wax or Hornady One Shot on the case body.
     
  4. AJ Peacock

    AJ Peacock Well-Known Member

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    Just back your resizing die off until you are only resizing down to 2.359" or 2.358", if they chamber easily in your rifle at that length, you are good to go.

    Easiest way is to back it off more than is needed and then adjust in, until you are pushing the shoulder back .001-.0015"

    AJ
     
  5. woods

    woods Well-Known Member

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    This picture might help

    [​IMG]

    the solid case head keeps the rear portion from expanding. The expansion starts where the brass thins

    The thinning is progressive so where it reachs the thickness of the rest of the case body is where the case starts to expand outward

    [​IMG]

    It is more a function of your chamber size than anything else and if you are not having a hard time chambering the case then you don't have a problem.
     
  6. guns_and_labs

    guns_and_labs Well-Known Member

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    "Back off" by moving the whole assembly up (i.e. getting further from bottoming out the die) or by moving the pin/expander ball thingie up in the die?
     
  7. AJ Peacock

    AJ Peacock Well-Known Member

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    Back the entire die up until you get just the right amount of shoulder bump. Then lock that down. The center (decapping assembly) needs to be down just enough to punch out the primers.

    AJ
     
  8. boomtube

    boomtube Well-Known Member

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    Just a thought on adjusting a FL die properly to just bump the case shoulder.

    I often see suggestions to move the die in "small increments, like 1/4 of a turn, until you get it right." Friends, quarter turns of a sizer is a MASSIVE change to a case; it needs to be in MUCH SMALLER increments if it's to do you any good.

    Consider that most SAAMI specs for bottle neck cartridges is around .008". A full turn of a 7/8x14 die moves it .0714", just over 71 thou. A quarter turn equals 17.85 thou, covering more than TWICE the normal allowable maximum range of headspace in just one adjustment! Adjusting your sizer in increments of 16th turn equals changes of 4.46 thou, or a bit over half the allowable headspace tolerance. That's certainly the largest amount of change you should make as you strive for proper fit to the chamber.

    I put a series of prick-pin punch marks on the upper face of my sizer die lock rings, 16 of them, as evenly spaced as I can make them. I use those marks as a reference for die changes. I can easily make changes of half the distance between the marks. That's not absolutely precise but it works fine in practice.

    The same sizing process IS valid for belted and rimmed cases as well.

    Simply do your resizing work off the shoulder for all bottle neck cases and you can prevent a LOT of "normal" brass stretching that presents the danger of early head seperations.
     
    Last edited: Aug 9, 2009
  9. kraky2

    kraky2 Well-Known Member

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    Boomtube is absolutely right and I have seen many posts with the incorrect info that he is talking about.
    REgarding why a belted magnum die doesn't size all the way to the belt ALL ordinary die makers leave a small safety zone so that the die can't hit the belt and move it. That way headspace stays where it was designed to be.
    A fl die should be set for about a .002-.003 bump of the shoulder from its full chamber dimensions in my book. Others may have slightly different opinions and you can set it even closer if all you are shooting is paper.
     
  10. AJ Peacock

    AJ Peacock Well-Known Member

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    Why would you need more than .001 clearance? In a hunting situation, I don't intend to shoot more than a single round, so getting dirt into the chamber isn't really a concern. If it gets dirty, I'll just clean it. Or am I missing something.

    AJ
     
  11. kraky2

    kraky2 Well-Known Member

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    It's just a limit I set. Come to Wisconsin and make deer drives with us through the brush and see what comes out of your gun at the end of the day!! Admittedly....there are far more "sterile" hunting conditions that you could Crush fit if you like.
     
  12. mo

    mo Well-Known Member

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    Best money you could spend if you shoot a belted magnum is to buy one of Larry Willis Belted Magnum sizing dies. It works wonderful! You still need a die to bump shoulder back because his only sizes from belt to where the shoulder starts. Larry post on LRH sometimes. The die is worth the money.
     
  13. kraky2

    kraky2 Well-Known Member

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    Yes...and Larry is getting "roasted" a bit on the next thread about sizing. I have one of his dies and it does what it says. It helped me reclaim alot of wby brass over the years from a couple custom guns with generous chambers.
    Do him a favor and give him a positive response on the next resizing thread.