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40/10 MM bullets

Discussion in 'Handloading and Reloading' started by Metalman1, Apr 5, 2013.

  1. Metalman1

    Metalman1 Well-Known Member

    Being new to reloading, I got confused on which was what. When I search for 40 S&W I find Hornady .400 10mm 155gr HP/XTP or I find 40/10mm .401. I thought 40 S&W was .400 & 10mm was .401. Can a .401 bullet go into 40 S&W brass?
    I should be getting my reloading gear mid April so I'm trying to have my stuff together. :confused:
  2. bds

    bds Well-Known Member

    Slug your barrel - http://www.youtube.com/watch?v=CR_WiL8Dkgw

    For 40S&W with .400" groove diameter barrels, I usually load .400" diameter jacketed bullets and .401" sized lead bullets.

    For .401" groove diameter barrels, .401" diameter jacketed bullets will provide better performance and you should use .402" sized lead bullets to reduce leading.
  3. GCBurner

    GCBurner Well-Known Member

    I think .400 is the standard for jacketed ammo, and .401 for cast lead or plated bullets. Both work in either 10mm or .40 S&W, and also in the old .38-40 Winchester cartridge.
  4. gamestalker

    gamestalker member

    Yes, jacketed .40 / 10mm bullets are .400", and lead / plated will vary. You need to slug your barrel if you intend to use anything but jacketed.

  5. ljnowell

    ljnowell Well-Known Member

    I wouldnt bother slugging the barrel. I would buy some lead bullets in the standard .401 and try them. Then see if I needed to slug my barrel, etc. Never had to do it yet on a handgun, and I certainly reload for plenty of them.
  6. sevt_chevelle

    sevt_chevelle Well-Known Member

    The 40sw and 10mm bullets ARE the same thing.
  7. Havok7416

    Havok7416 Well-Known Member

    They are one and the same. I reload for 10mm and .40 out of the same box of bullets.

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