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Does Dillon's sizing die expand the case mouth?

Discussion in 'Handloading and Reloading' started by jski, Sep 26, 2017.

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  1. jski

    jski Member

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    Talked to a Dillon technical rep today and he asserted that the sizing die does not expand the case mouth. He stated that there's an expander built into their 550 progressive "powder fill stage". (I'm using an RCBS press.)

    But the "instruction manual" (1 sheet of parsimonious prose) states:
    Where lies the truth?
     
    Last edited: Sep 26, 2017
  2. ljnowell

    ljnowell Member

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    What cartridge are you loading? Their rifle dies will have a neck expander. Their pistol dies obviously won't.
     
  3. 444

    444 Member

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    Both statements are true.

    As the last guy pointed out, with rifle dies the die sizes the neck then the neck is pulled back over an expander ball. The die sizes the neck smaller than what you want, then the expander ball determines the final neck diameter. This is not the same thing as flaring the case mouth.

    With pistol dies, the case mouth is flared in a separate die. The sizing die only sizes the case.

    In a rifle die the neck is resized and then pulled back over the expander ball (part of the decapping pin) in the sizing die.

    With pistol dies, expanding the case mouth is done with a separate die. With Dillon dies this is also the die where the powder dump takes place. The sizing die does not flare the case mouth in either case.

    If you look at die sets for sale (not Dillon), you will see typically pistol die sets are three die sets and rifle dies are two dies. This is why. With Dillon, the dies are for a progressive loader, so you still need a third die where the powder drops (basically just a hollow tube that screws into the press like a die. Again, with pistols this die flares the case mouth and the powder flows through it. With rifles it just drops powder.

    If you are loading cast bullets in a rifle case the case mouth needs to be flared to seat the bullet but this again is a separate die that typically does not come with the die set. It is a separate specialty die. With jacked bullets in rifles the case mouth is not flared.
     
    Last edited: Sep 26, 2017
  4. jski

    jski Member

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    The die set is for the .30 Carbine. I assume that puts it in the rifle category.
     
  5. cfullgraf

    cfullgraf Member

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    Even though 30 Carbine is considered a rifle cartridge, it is more like a straight walled pistol case. With conventional dies, mouth expanding happens with a separate die.

    Mouth expanding of a 30 Carbine case cannot happen in the sizing die like what would happen with a bottle neck rifle case.

    So, a Dillon 30 Carbine die set would include a sizer, a bullet seater and a crimp die. Mouth expansion and flare would occur with the drop tube in the powder measure.
     
  6. 444

    444 Member

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    "Mouth expanding" doesnt happen in either sizing die.

    NECK expansion is done in most rifle sizing dies. Bottle necked rifle cases.

    MOUTH flaring is done in pistol dies, but not with the sizing die.

    .30 Carbine would be a three die set. It doesnt have a neck. The mouth is flared (not in the sizing die) Flaring the case mouth facilitates the bullet freely entering the case when you seat the bullet. This flare is later taken back out by the crimp after the bullet is seated.
    In rifles the diameter of the neck is a very critical dimension. It determines the neck tension, or how hard the case holds the bullet. Consistent neck tension is critical to accuracy. Having the case neck square to the case body is important. Having consistent neck thickness is important to accuacy.

    Long story even longer: flaring a case mouth, and expanding a case neck are not even close to the same thing and are done for totally different reasons.
     
    Last edited: Sep 26, 2017
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