7mm 180gr SMK

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by cummin_un_glued, Jul 31, 2013.

  1. cummin_un_glued

    cummin_un_glued Well-Known Member

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    The 7mm 180 grain HPBT MatchKing was created in response to requests from top-level F-Class shooters. Sierra has designed these MatchKing to provide a higher weight/higher B.C. alternative in our 7mm line. This bullet's 12 caliber secant ogive and lengthened boat tail make it the perfect choice for the discerning 7mm long range shooter.



    Please Note!! This bullet requires at least a 1x8" twist barrel.

    my rifle on order has a 1-9 twist brux

    has anybody tried these in a 1-9?
     
  2. LouBoyd

    LouBoyd Well-Known Member

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    The required twist rate for a given bullet is a function of several things. Most important are the air density and the bullet muzzle velocity . At supersonic velocities most bullets are more stable the faster they are driven. The force of air trying to upset the bullet is higher but the spin rate is faster and is a little more important.

    Cold dry high barometric pressure air is denser than warm moist low barometric air. Denser air requires a faster twist rate. A 9 inch twist barrel with a 280 or higher velocity cartridge shoots 180 SMK and Bergers just fine at the mile plus altitude in Arizona where I shoot most of the time. At that altitude even sub freezing temperature is not a problem. At lower elevation and colder temperatures I can't say.

    The best way to find out if a given bullet will be stable in your rifle in the conditions you'll be shooting is to shoot some long range targets for group size in conditions with a little higher air density than you expect to hunt in. Asking on the Internet if they shoot OK or using computer stability simulators like McGyro is is far less reliable.
     

  3. cummin_un_glued

    cummin_un_glued Well-Known Member

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    I understand all of that. I was looking for first hand experiences. Plenty of guys on here that shoot the 7mm's of various kinds so I figured at least a few have tried it and could save me the trouble. the gun is being chambered in 7mmx300win so it will be plenty fast. I guess I will just load some up and try it when it gets here. i'm at 500ft and I hunt at 7500ft so if it shoots good here it should shoot even better in WY.
     
  4. APEX

    APEX New Member

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    I have a 9 twist and a 8 twist in 284 win. There both 28 inches long. I can't tell the difference out to 1200 yards shooting the SMKs.
     
  5. cummin_un_glued

    cummin_un_glued Well-Known Member

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    thank you sir
     
  6. Dick Tinsley

    Dick Tinsley Well-Known Member

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    Sorry! Hit the wrong button, with the quote! I too have a 7/300 being built now! I even had my reamer made for the 180 SMK's! After everything I read in the other thread concering the 7/300, I really don't think you'll have any problem! I own three 7mm an only one of them really doesn't like the 180's, the other two shoots them pretty good. Just my 2cts!!

    DT
     
  7. Dick Tinsley

    Dick Tinsley Well-Known Member

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    The 7/300 I'm building has a 28in keriger1n9 twist!

    DT
     
  8. cummin_un_glued

    cummin_un_glued Well-Known Member

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    awesome I think the next "brotherhood" will be the 7x300 brotherhood since there seems to be a fair amount of them being built on here. mine is being reamed for 180 bergers but i'm going to try all of the 180gr's and see what it likes the best
     
  9. Dick Tinsley

    Dick Tinsley Well-Known Member

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    Trying differant types of 180's is a good idea. I've just got a limited supply of Sierra an Berger's so for now that's what I'll load with!! As far as a 7/300 brotherhood, count me in!!!!
     
  10. JeffVN

    JeffVN Well-Known Member

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    If memory serves the Sierra 1:8 twist statement was based upon their belief that someone would try to shoot the 180s from a 7x.08. I have shot them from my 7WSM (matches and the desert in and around Las Vegas) and my brother from his .284 Winchester (California not much above sea level) from 1:9 twist barrels with no problems.

    Jeffvn
     
  11. cummin_un_glued

    cummin_un_glued Well-Known Member

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    awesome news now I just gotta gather up some bullets. I am picking up a couple lbs of RL33 tomorrow to try
     
  12. Dick Tinsley

    Dick Tinsley Well-Known Member

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    Keep us informed on the performance of the RL33. I've been wondering about that stuff, just haven't found any rocksolide data on it! Like I said in a earlier post, I don't think that you will have any problem with the 180 SMK. Like I said, two of my 7mm will shoot the heck out of them, the third one will, it just doesn't like em! Guess its just one of those barrels that won't shoot em! But that's being taken care of now!(rebarrel) Just my 2cts!

    DT
     
  13. cummin_un_glued

    cummin_un_glued Well-Known Member

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    Well I picked up a couple pounds of the RL33 today. the shop had 8lb so if it likes it I will go back and get what ever they have left at that time. I will keep everyone posted as I start development. I still need to find some Retumbo. I plan to test the following powder and bullets...

    H1000
    Retumbo(still got to find)
    Reloader 25
    Reloader 33
    Vihtavuori N560

    180 berger hybrid (if I can find some)
    180 SMK
    180 JLK

    This will probably be the end of this thread since my question has been answered. I will start a new thread with all of the development data around the end of the month when I get the rifle back.

    Thanks for everybody's input!