7mm WSM size up .270 or size down .300?

Discussion in 'Reloading' started by bwaites, Sep 21, 2009.

  1. bwaites

    bwaites Well-Known Member

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    What to do, what to do?

    I want to use Norma brass to improve consistency, but I'm not sure if sizing up .270 WSM brass or sizing down .300 WSM brass is a better option.

    Any thoughts or help is appreciated!

    Bill
     

  2. J E Custom

    J E Custom Well-Known Member

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    Bill.

    I would use the 300 WSM brass if I could not get the 7 WSM brass in the make I wanted.

    You could size down the 300 brass and then turn the necks to true them and still have nice
    thick necks that are uniformed.

    Even the 325 WSM could be used but no matter which one you use you will have to fire
    form the brass for the 7 WSM.

    J E CUSTOM
     

  3. bwaites

    bwaites Well-Known Member

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    Does that increase the risk of the infamous "donut"?

    It's what I was thinking, but I've never done it, so wanted some advice!

    Bill
     
  4. J E Custom

    J E Custom Well-Known Member

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    Anytime you neck size up or down you run the risk of ballooning if the necks are not lubed
    well. ( I lube inside and out when doing this ).

    Even when expanding up you have to force the expander ball down the throat of the neck
    risking ballooning . So I use a swab soaked in sizing lube and do all of the cases on the
    inside.

    Good luck

    J E CUSTOM
     
  5. bwaites

    bwaites Well-Known Member

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    Thanks, much appreciated!

    Bill
     
  6. MagnumManiac

    MagnumManiac Well-Known Member

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    I don't believe you can neck the others up/down to 7mmWSM due to the shoulder being further forward.
    You could neck down from 300WSM brass and leave an auxillary shoulder to headspace off, but that alone can cause problems.
    You would have to use a fireforming load, shotgun powder, cream 'o' wheat, and something to plug the case mouth like pumpkin or potato. This may eliminate the donut, but it may not also!
    I think it's too much trouble bothering with, IMHO.
     
  7. geargrinder

    geargrinder Well-Known Member

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    I'll disagree. I've done both with excellent results. I've necked up with 270 and necked down with 300.

    With the 270 brass, I just jammed the VLD a little into the lands and used a mid range powder load. Perfect fireforms and accurate loads.

    With the 300 brass, I left the false shoulder and used the same load and OAL. Yes, the necks were a little thicker, but were not an issue in my chamber.

    Definitely worth the trouble. The Norma brass is way better, makes the Win and Rem brass look like junk.
     
  8. mo

    mo Well-Known Member

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    I neck up up the 270wsm norma brass to 30 cal. then back down to 7mm. I do this to create a shoulder.
     
  9. geargrinder

    geargrinder Well-Known Member

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    Yep, done that too. That's when I tried to just shoot them with a jammed bullet. That worked so I decided it was just working the brass more than needed.