case trim pilot correct size but inside case dimensions too small.

Discussion in 'Reloading' started by partisan1911, May 22, 2010.

  1. partisan1911

    partisan1911 Well-Known Member

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    After I resize my .338 case I am getting ready to trip so I put it on my RCBS case trimmer with the appropriate shell holder and pilot. The pilot measures .338 but the inside case neck measures .328

    So the pilot won't go inside the case neck and thus making it not possible for the teeth to meet the case and trim appropriately.

    What am I messing up?
     
  2. bassin93

    bassin93 Well-Known Member

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    do you have the correct expander ball in your sizing die?
     

  3. winmag

    winmag Well-Known Member

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    1. Check your sizing die. Do you have an 8mm expander ball or a bad 338 ball?
    2. How many times have the cases been fired? you may be nearing the end of your case life, and have too much neck thickness. Are some of the cases splitting/cracking on the necks when you re-size?
     
  4. Mikecr

    Mikecr Well-Known Member

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    Doesn't it seem pretty obvious that a pilot measuring .338 will never work for SIZED 338 cartridge brass necks?

    What do ya think the problem is?
     
  5. partisan1911

    partisan1911 Well-Known Member

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    Thanks for the useful comments. I am using redding FL sizing die for my .338 Lapua. The cases have been fired once with no indications of high pressure after firing or cracking etc after sizing. Possibly the expander ball is not correct or I have them adjusted incorrectly? Obviously the inside case measurment needs to be just snug enough to hold the bullet in place for seating purposes but I don't know what that exact measurement is supposed to be. I bought two pilots for my trimmer thinking that maybe one was sized .338 on accident and a new one might be sized slightly smaller to fit inside the case but labeled for a .338 caliber. I also have a different brand of dies on order so I can measure the differences between the two.

    mikecr, thanks for your help?
     
  6. boomtube

    boomtube Well-Known Member

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    What Mike wants you to understand is the neck inside diameter has to be at least as large as the pilot, ideally a thou larger for easy trimming. Sometimes we have to trim fired cases because of the need for some pilot clearance.

    The neck ID is determined by the expander ball, not the die itself. A neck that's some 10 thou smaller than the bullet is NOT right. Ideally it will only be some 1 or 2 thou smaller than the bullet. Any higher bullet "tension" only increases the required seating pressure (but not real bullet pull/tension) AND increases bullet run-out, which is harmful to accuracy.
     
  7. partisan1911

    partisan1911 Well-Known Member

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    I pulled my FL die and NK dies apart to compare the expander balls. The NK die is .336 and the FL is .308.

    I assume I can take the one off the NK and use it in the FL die? Does this mean when I bought the set it came with the wrong expander ball in the FL die? I bought the set new.
     
  8. Gunpoor

    Gunpoor Well-Known Member

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    It sounds like the sizing ball in your die is too small. The neck sizing ball should be about .0015" smaller than bullet diameter. I have put a trimmer pilot into a drill and used some emery cloth to slightly reduce the diameter of the pilot to make it fit into the case necks easier but this is usually not necessary. BTW, getting the pilot into the cases for trimming is the least of your problems, as the reduction in sizing then the expansion of firing is working the he!! out of your brass. Maybe the new dies you are getting will solve the problem. Redding has great customer service and will correct any real problem with their dies. I know this from personal experience with them, and they are first rate. I have also heard of guys turning the stem from the sizer die in a drill while holding emery cloth in their fingers to polish and reduce the ball size, but yours seem to be way too far out of spec. Good luck and hope you can fix this problem.
     
  9. justgoto

    justgoto Well-Known Member

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    I would not switch parts around.
    Yes it is the wrong expander ball.
    I would send/take the dies back to where I purchased them and get a new set.
     
  10. boomtube

    boomtube Well-Known Member

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    "I assume I can take the one off the NK and use it in the FL die?"

    Sure, why not? That will clearly solve your immediate problem until you can get it corrected.



    "Does this mean when I bought the set it came with the wrong expander ball in the FL die?"

    Unless you or someone else swapped it around, it appears so.



    "I bought the set new."

    Okay. Now take it back. :)
     
  11. Mikecr

    Mikecr Well-Known Member

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    This is but another example of reloading issues discussed here that once again, resolve to use of FL dies -as a shortcut.
    Two problems here that NS/body die users don't get into because:
    1. We don't use/need expanders
    2. We think about what it is that we're actually doing to our brass, while we specifically adjust for it. We choose our bushings, and measure our shoulders.. And everything works to a plan..
    None of this slap hazardly running brass through a single die, and assuming it magically does it all correctly, unless results are so far out of whack that questions 'must' be asked about it..

    But anyway, off my soapbox..
    Even when you fix the sizing issues, that 338 trimming pilot will NOT work for sized brass, right?
    So fixing a die won't help you there.
    You'll need to trim pre-sizing or turn down the .338 pilot to about .334 for post-sizing use.
    But, if you trim pre-sizing -while following with FL sizing, then case length will end up inconsistant. This is because FL sizing lengthens cases based on the amount of it's over-sizing.

    So the solution to your original problem is use a correct size trimming pilot, post-sizing.
    Turn it down, or use another that's right.
     
  12. boomtube

    boomtube Well-Known Member

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    1. We don't use/need expanders
    2. We think about what it is that we're actually doing to our brass, while we specifically adjust for it. We choose our bushings, and measure our shoulders.. And everything works to a plan..None of this slap hazardly running brass through a single die, and assuming it magically does it all correctly, "


    Mike, you were doing good but now, with magic neck "bushings", you've done gone too far!

    All a bushing can do is make the necks consistant, or nearly so, on the outside so the insides vary due to normal neck inconsistances. On the other hand, all an expander can do is make the necks consistant, or nearly so, on the inside. If that inner consistancy matters to anyone. It does to me.

    Mostly meaning that neither neck sizing system is perfect if it stands alone. ;)
     
    Last edited: May 23, 2010
  13. partisan1911

    partisan1911 Well-Known Member

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    So I plan on using a different expander ball and polish down the trim pilot.

    I guess it was just bad luck on the size of the expander ball and bad marketing on the trim pilot.

    Both of the trim pilots were the same size of .338. I would have thought the manufacturer made them for the .338 caliber but corrected the size to fit inside the neck.

    If using FL dies is a shortcut, what other dies am I supposed to use if not getting custom dies cut?

    I figure if I run the brass through the die with the right expander ball, trim to size, trim the outside of the neck, I would be tracking with some good brass. Maybe not benchrest but it should work for some decent long range hunting brass?
     
  14. boomtube

    boomtube Well-Known Member

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    "So I plan on using a different expander ball and polish down the trim pilot. "

    Well, think of it a little differently: you will use the CORRECT size expander and see how the current pilots work. And lube the pilots/necks with case lube to reduce friction.