Resizing Lapua .300 Win brass to .338 Win

Discussion in 'Reloading' started by tacsniper0888, Aug 18, 2012.

  1. tacsniper0888

    tacsniper0888 Well-Known Member

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    Hey guys I need some help. I'm looking for the best possible brass that I can buy for my .338 Win mag Remington 700 Sendero build I'm in the process of. I read where Lapua brass is the best on earth but also that they don't make any in .338 Win mag, yet they do in .300 Win mag and that I could buy the .300 and neck it up then full length resize in my current RCBS FL .338 die and be good to. I'm new to all this and don't have the slightey clue as to where to begin so any and all information is great appreciated. Thanks guys.
     
  2. Stonewall2

    Stonewall2 Well-Known Member

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    That Lapua .300 brass is discontinued stock if you can find any.
    It was made by Norma for Lapua.

    You can run .300 Win thru your .338 die with out the expander assembly to set the shoulders back to match your chamber .

    Then trim case to -.025 less than the neck length of the chamber .

    If you use Norma brass you will find a step where the base of the old .300 neck was .
    This is because the necks are inside reamed durning the case forming process.

    It helps to anneal the necks with a candel flame for about seven seconds-f.l. size again and neck turn.


    I make 7mm Rem from .300 Win. to headspace on the shoulder for the first firing.
    If you measure factory belted magnum rounds with a RCBS case mike the shoulder epands forward a LOT on the first firing in a SAAMI chamber.

    http://www.saami.org/PubResources/CC_Drawings/Volume Cover.pdf


    Glenn
     

  3. 358sta

    358sta Well-Known Member

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    I'd just purchase Norma 338 Win Mag brass and be done with it. It isn't as good as Lapua but it won't require as much work either.

    Do you have a source for the Lapua 300 Win Mag brass? I haven't seen any for some time.

    Kevin
     
  4. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Why don't you just use 7 rem brass if you need other brass in a 338 win like I do. I ended up in a situation last year where I had 7rem brass coming out my ears and I was short on 338. I ran the 7rem's through a 300 die, then final formed them in my 338 win die. They shoot fine, but win brass has rather low neck tension, so I only use rem brass. The original neck thickness combined with standard dies is doing this.
     
  5. Gene R.

    Gene R. Well-Known Member

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    Also, the 338win isn't hard on brass. So, if you sort win or rem cases for consistency and get a good stash there going to last while. I find it's my best casing life of all my calibers. I have 338 brass coming out my ears it lasts so long.

    Gene
     
  6. tacsniper0888

    tacsniper0888 Well-Known Member

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    Do you have any you would like to sell?
     
  7. Gene R.

    Gene R. Well-Known Member

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    pm'd