Pennsylvania Firearm Owners Association
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  1. #1
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    Default Seating die stem for .357 mag

    I've noticed that my seating die consistently deforms my bullets during the seating process (see pictures). I've read that the seating die stem can be replaced to accommodate different bullet types, but I'm not sure how to tell which stem to buy, or whether it will work with my dies.

    Has anyone seen this problem before? Any stem recommendations for this type of bullet?

    I'm using Lee carbide dies and the bullets are nosler sporting handgun 158gr. JHP.

    https://imgur.com/a/VvKEiBd

  2. #2
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    Default Re: Seating die stem for .357 mag

    Seen it a lot. The seating stem is pushing down on the wrong part of the Ogive of the bullet. You can either have your local machine shop carve you a new one or contact Lee. If you send them a few bullets they will custom make you a seating stem for free plus shipping.

    Since I bought a lathe I make all my own custom seating stems.

    The one you may need may or may not exist. Its kinda of a trial and error thing based on the shape of the bullet . But usually its a one size fits most type of deal.
    Last edited by DucatiRon; May 8th, 2018 at 07:56 AM.
    www.Steelvalleycasting.com is your new home for coated bullets and custom ammo.

  3. #3
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    Default Re: Seating die stem for .357 mag

    Great, thanks for the info! I'll get in touch with Lee.

  4. #4
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    Default Re: Seating die stem for .357 mag

    Looking at your pics it appears your applying quite a crimp. Sometimes if hard crimp is applied before bullet fully seated you can get some funky signs. I'd back the die off with minimal/no crimp, seat a bullet, and see how they look. If ok then adjust for crimp. Check with micrometer if you have one, if not look at some factory rounds or pics to duplicate.
    Last edited by cephas; May 8th, 2018 at 08:16 AM.
    It ain't what they call you, it's what you answer to.

  5. #5
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    Default Re: Seating die stem for .357 mag

    That crimp is just from the seating die (I think it does both). Maybe the bullet deforming so much caused excessive crimp? Or maybe I just have my die set up incorrectly.

    I definitely will not be firing these...

  6. #6
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    Default Re: Seating die stem for .357 mag

    It looks like you're starting the crimping well before the bullet is seated.

    Back off the seating/crimping die from the top of the press about a 1/4".
    Unscrew the seating rod 3 or 4 turns, or more.
    Start a bullet with your fingers.
    Run the round up to the top of the ram movement.
    Then screw the die in until you feel it just touch the case mouth, at this point the crimper portion of the die is touching the bell portion of the case mouth.
    Screw the seating rod in until the bullet is at the proper depth (you will have to lower the ram to check, do it little by little). This will set the bullet depth without putting any crimp on it.
    Once the bullet is at the depth you want, lower the ram and turn the seating rod out by one turn and turn the die in by one turn and run the ram up to seat/crimp.
    Lower the ram to see how the seating depth and crimp are and make slight adjustments to the seating rod and die from there.
    Just remember, if you lower the die into the press, you'll want to move the seating rod out by the same amount. This way, once the ram is all the way at the top you will have seated the bullet to the correct depth and crimped it at the last small movement of the ram going up.

    Hope this helps.
    Ron USAF Ret E-8 FFL01/SOT3 NRA Benefactor Member

  7. #7
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    Default Re: Seating die stem for .357 mag

    I have been using the same ole RCBS carbide .38/.357 dies set for 25+ years w/o a problem. I broke a decapping pin once on some damned berdanprimed foreign case wh somehow got into the hopper???? I always play around with a load using a case w/o primer or powder tho be4 loading any live rds...to adjust seating depth, crimping etc... ya gotta crimp them some to keep 2nd or 3rd rd projectiles from slipping OUT and thus stopping the cylinder rotations..ask me how I now this ;-)
    My only problems seem to be very occasionally I slipup and drop a bullet wh is "tipped over too far" off true, and that crushes the case mouth.
    Last edited by Fred762; May 8th, 2018 at 10:54 PM.

  8. #8
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    Default Re: Seating die stem for .357 mag

    Thanks for the tips! I'll try again and report back after I get a new stem.

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