7WSM and long action ?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Kalashnikov, Dec 23, 2007.

  1. Kalashnikov

    Kalashnikov Well-Known Member

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    I am considering building a 7WSM specifically around the 162 A-MAX (.625 BC) or Berger 168 VLD (.643 BC) and 1-10 twist barrel.

    I want to maximize the powder capacity (and velocity) of the case, so the plan is a cartridge overall length based on these bullets seated to a maximum .284" into the case neck (or less - what is the minimum I can get away with ??). I will also have the barrel/chamber throated so that the bullets would touch the lands when seated to this cartridge COL.

    Lastly, I do want to use the magazine of the rifle. I suspect I cannot use the magazine on a short action with this proposed COL (whatever that may be - not sure at this point - anyone ??). Therefore, I am considering custom chambering a new long action SPS or Savage 110 (in 300 RUM as a donor action?) to this cartridge spec.

    Any problems I may be getting into with this build ? Can I expect much of an improvement in performance over a short action with these bullets seated to 2.86" COL ? Any advice or thoughts would be appreciated.
     
  2. dwm

    dwm Well-Known Member

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    The detachable magazine length of the short action Savage model 16FCSS is 3".
     

  3. Kalashnikov

    Kalashnikov Well-Known Member

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    I am 'estimating' the COL with the 162 A-max seated -.284" into the case neck to have a COL of around 3.5".
     
  4. Blacktail2

    Blacktail2 Well-Known Member

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    I have a custom 7wsm built by Chris Mathhews on a Stiller Predator short action with a watts extended magazine.My O.A.L. to the lands is 2.974 with the amax.This combo works with a little room to spare in the Watts box.

    If you measure from the start of the boattail up .284(which the min. i like to have)you get a O.A.L. of about 3.029.I don't were you got the 3.5.

    My 7 shot the amaxs ok but it liked the 175mk and the 176 Cauterucio the best.
     
  5. Kalashnikov

    Kalashnikov Well-Known Member

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    The 3.5" may be a bad estimate. I won't argue 3.029" - thank-you. What is the OAL with the 175 SMK's ?
     
  6. dwm

    dwm Well-Known Member

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    Now we are getting somewhere. Would a 3" detachable mag be ok then with the proper throat?

    Would this be close enough, does one really need a long action?

    Then what about the 168 Berger and maybe even the 180 Berger? (I'm kind of hijacking your thread, but it is to the same question ...)
     
  7. Blacktail2

    Blacktail2 Well-Known Member

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    Kissing the lands lightly 2.965 loa. The base to ogive(which is a better measurement) is 2.311 with the 175MK.
     
  8. RockZ

    RockZ Well-Known Member

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    I made a dummy round with the beginning of the bearing surface of a 168vld just to the neck/shoulder junction and it measures 3.13" OAL.
    Hope it helps.
     
  9. Kalashnikov

    Kalashnikov Well-Known Member

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    Is the 2.965" OAL for the 175 SMK when the bullet is seated max .284" into the neck ? If so, looks like a LA may not be required after all..tnx
     
  10. Kalashnikov

    Kalashnikov Well-Known Member

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    Yes thank-you. It looks like a 3.1" short action would pretty much accomodate these bullets just fine...interesting...
     
    Last edited: Dec 23, 2007
  11. Blacktail2

    Blacktail2 Well-Known Member

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    I just measured the max O.A.L. that will fit in the watts box,and its 2.995.This is a short action.If you need more, than the long action is the way to go,or the Savage.

    Kalashnikov,
    The 175mk load is seated about .350 into the neck.
     
    Last edited: Dec 24, 2007
  12. Kalashnikov

    Kalashnikov Well-Known Member

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    What kind of velocoties are you guys getting with your 162 A-Max and 175 SMK's ? Loads ?

    Maybe the M700 SA with Wyatts box extended magazine is the way to go....

    Good info. tnx
     
    Last edited: Dec 24, 2007
  13. JeffVN

    JeffVN Well-Known Member

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    I'm getting 2,900 fps from my 7WSM with the Sierra 175 smks using a 26" Kreiger 9 twist barrel and a overall length of 2.860" My load is 65.0 grains of RL-25 or 66.4 grains of H1000 (a little slower - 2,875).

    My current set up is magfed from AI magazines through a Surgeon Short Action.

    JeffVN