180 SMK in 7mm 9.25 twist? what to do?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by dancrockett, Mar 17, 2013.

  1. dancrockett

    dancrockett Member

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    I bought 1100 SMK's for my 7mm rem with the 26", 9.25 barrel. Then I read Sierra's warning about "8 twist or faster". I ran this bullet through the Miller twist rule calc. and can get it to the 1.5 "comfortable zone" at 2800fps, 70 deg temp @500ft elev. but that means max loads.
    I also have 500 Berger 180gn hunting bullets, and they recommend a 1/9 twist barrel, but running the same parameters except for bullet length I get a stability factor of 1.36. Having zero experience, Is it safe to shoot these? Do I sell/trade them all? do I file the tips to shorten them up to get to 1.5+? What would you do?
     
  2. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Re-chamber to 7mmstw-- shoot bullets.... problem solved....

    Shoot a few and see in your 7rem....... I sure as heck wouldn't open any more boxes than you need to work with though. You've got enough pills to wipe the bbl. throat out pretty well if they all go through one rifle.
     

  3. dancrockett

    dancrockett Member

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    I'm not going to shoot any if they're no good at 9.25, which is what I'm trying to find out.
     
  4. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    over on the 7mm stw brotherhood thread there are a few guys using the 180 hambergers.... post up on there if you want but I've shot out a few 7's out and a 9.25 should be enough twist. The 7 rem is a bit small though to get the speed up enough.
     
  5. Niles Coyote

    Niles Coyote Well-Known Member

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    Using the Miller twist rule calc on JBM ballistics have had good results with bullets that scored above 1.15, lower than that and I would run into problems. I suspect you will have zero problems with a 1.3 rating. This calculator has been very helpfully pushing long heavy weight bullets in Remington’s slow twisted (1-9)223 and (1-9.125)243...
     
  6. dancrockett

    dancrockett Member

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    Thanks Niles, It is a little confusing because Sierra calls for a 1/8 and Berger calls for a 1/9, and the SMK's are a little shorter and have higher stability than the Bergers, 1.43 vs. 1.31 w/1/9.25 barrel
     
  7. J E Custom

    J E Custom Well-Known Member

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    +1 the 7 STW with its larger capacity will do fine with the 1 in 9.5 twist also the 7mm RUM would be
    a good choice if you decide to go with the a new chamber.

    The other option with the 7 RM in 1 in 9.5 twist would be to sell or trade the 180s for some 168 SMKs.

    With careful loading you might get the 180s to work. It would be worth a try. (Whats 20 or 30 bullets
    worth).

    J E CUSTOM
     
  8. antitactical

    antitactical Well-Known Member

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    Go STW. I've got a sako 995 in 7mmstw. It has a 9.25 twist and hammers berger 180vld hunting bullets running them just at 3000fps.(thats also a light load for the stw) Your bolt will work all that has to be done is the chamber cut out to stw and you should have no headspace issues. It should be a fairly cheap job too being that the barrel doesn't have to be cut or rethreaded.