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Thread: Do I need a neck expanding die?

  1. #1

    Do I need a neck expanding die?

    Hi everybody, I have a Lee 3-die set for .38 Special/357 Magnum. I have only ever loaded jacketed and copper plated bullets with it, but am planning on loading up some lead "boolits" soon. Do I need a neck expander die? I'm pretty sure all my expander die does is bell the case mouth. I'm planning on using 180 grain gas checked boolits, if that makes any difference.


  2. #2
    Boolit Master
    Join Date
    Feb 2013
    Upstate, SC
    Quite simply....yes. If just belling the case mouth when loading lead bullets, then you're effectively swaging the bullets into the case....thus reducing their diameter.
    "Do not follow where the path might lead, go instead where there is no path and leave a trail" Ralph Waldo Emerson

  3. #3
    Boolit Bub
    Join Date
    Sep 2017
    Near that little town in Eygpt or SW Wyoming, whichever
    I respectfully suggest, that you need to read the instructions that came with your dies. All of the Lee dies I have used did expand the cases as well as bell the mouth. The big question is, is it enough. That will have to be determined by measuring the cases both before and after running them through the die and then checking them against the bullet you are using. Then you can determine if you need an additional expander die. (M type or something of that sort.) I have never had an issue with the regular expander and I have loaded several hundred thousand 38 specials with both cast and commercial swaged bullets and never had an issue. HTH

  4. #4
    Boolit Buddy
    Join Date
    Jan 2011
    Prineville, Oregon
    I've got an "M" die or the NOE equivalent for all rifle calibers I load but never felt the need for pistol stuff since the die sets have the bell/expand die included. Load 'em and shoot 'em.

  5. #5
    Boolit Master

    randyrat's Avatar
    Join Date
    Jan 2007
    North West Wisconsin
    Depends on the die set and hardness/kind of your brass. You can check your die to see if it expands the inside of the mouth enough for cast bullets.
    First die you use deprimes and resizes, there is a so called "Spud" on the depriming rod, this expands the inside of the neck. This spud can be replaced.

    Most die sets are make for Jacketed unfortunately for us. Maybe someone can chim in here and let us know who is selling replacements now.

    Jacked bullets need much more brass squeeze/ hold then lead= about ~.004 to .006 smaller than bullet to hold and make up for brass spring back

    Cast do much better than Jacketed with a ~.001-.004 inside neck smaller than cast. This also prevents the brass from squeezing your cast bullets down and causing leading from undersized bullets.

    You won't hurt my feelings if you want to argue or enlighten us with numbers that work better

  6. #6
    Boolit Buddy quail4jake's Avatar
    Join Date
    Dec 2015
    The North Woods of Pennsylvania
    Treat yourself, go to NOE's website and look at their expanders the work with the lee expander die, pick a few sizers that are close to your boolit diameter minus .002-.004 and fit to just enough tension to hold. No more fuss!

  7. #7
    Boolit Master gpidaho's Avatar
    Join Date
    May 2014
    Beautiful Idaho
    SP99: Like everything else in our hobby, one size does not fit all. A bullet cast of 30 to 1 alloy requires less neck tension than one cast of an alloy of 20+BHN. Too mush tension on a soft bullet and you will swage it down and get barrel leading. Too little neck tension on a hard cast bullet and it won't expand to seal the hot gases. Once again causing a leaded barrel. I use 1 to 2 thousands on soft alloy and 3 to 4 on hard cast. And, as mentioned above , the NOE tools are a great way to get you there. Good shooting. Gp

  8. #8
    Boolit Grand Master
    Join Date
    Aug 2005
    South Jersey
    I'm pretty sure all my expander die does is bell the case mouth.
    That's all that needs to be done. Expand the mouth so 1/2 of the bullet base sits in the mouth - to preclude lead stripping when fully seated

  9. #9
    Boolit Grand Master

    Join Date
    Mar 2013
    Northwest Ohio
    While not totally necasary, You can load cast by just belling and it may work with harder bullets. The different size expanders are another tool in the box for you to use to fine tune everything together. Neck tension can and does have a definite effect on accuracy. In very accurate firearms this can be seen when adding or lessening tension. The only way to tell is to try it. With cast bullets it is a concern of swaging bullets down with heavy tension also. On long small dia bullets there is the possibility of deformation or bending when seating also. The different dia expanders can adjust for this.
    There are several ways to control tension. Expanders are one. a die and expanders are used on brass sized to small to open it up to what to you want/need. This works regardless of brass thickness. Another is a bushing die that sizes brass to just what you need. Advantage is brass lasts longer since its not being oversized and expanded back up. Draw back is different brass may vary in wall thickness requiring different bushings. If you have all the same brass and a life time supply the sizer die can belapped or polished out to achieve this also. but again its only good for the brass its set to for the sure thing. The expanders are a good way to go and sometimes a insert can be purchased to go into your existing die sets expand bell die and not take the extra step.

  10. #10's more complicated than I thought. Well, of course it is, why wouldn't it be? These boolits are from Cast Performance and are 18 BHN, I think. They are only .357" in diameter. I'm going to be loading these up pretty hot using Starline brass, H110 powder, and CCI 550 primers. Does the gas check make any difference? I would think that the copper gas check might do the expanding as the boolit is pressed into the case, leaving the lead unswaged. Yes? No? Maybe? Anyway, I'll get those instructions out and figure out exactly what I'm dealing with, and thanks for the advice so far.


    EDIT: After looking at a diagram of the Lee Powder Thru Expanding Die, it appears that there is a section that goes down inside the cartridge case before it gets to the part that bells it. So, I guess you just get a replacement part from NOE that is made for a .357" diameter cast bullet? I think for starters I'll just load a few and see how they look. Maybe pull one or two and measure them to see what's going on.

    Last edited by scottyp99; 12-17-2017 at 05:16 PM.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check