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Thread: Introducing the 270 Montana

  1. #1

    Default Introducing the 270 Montana

    UPS delivered these to me a couple days ago. I had some 300 Dakota brass laying around here so I decided to do something with it.

    The case on the left is a WSM and the one on the right is a RUM.

    The 270 Montana will have about 4 H2O gr more capacity than the 270 WBY and about the same as the STW.

    I plan on shooting 160 -175 gr bullets in this cartridge. Matrix has 165's, 170's and 175's. Cutting Edge has a 165 that will need a tight twist. I'm expecting 3200-3300 fps velocities. RL33 will probably be the powder of choice.

    This is my first wildcat other than a 6-284 and 6.5 WSM which I don't consider wildcats



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  2. #2
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    Why not 6.5 or 7 mm to get a more aerodynamic bullet selection? I like the case design, what is the length, and will it fit a 3.35" action?

  3. #3

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    The case itself will be about 2.540" in length. So what ever bullet protrusion you have will determine if it fits in a particular action. This rifle will be built on a Howa or Vanguard action which a mag length of about 3.56 which will make it a tight fit for the long high BC bullets I'll be using.

    I just finished a 6.5 WSM and dont "need" another ATM, but I do have plans for a 264 Montana that will be based off either the 7 Dakota or 300 Dakota depending on the performance of this cartridge and throat wear. I will be nitriding the barrels of my rifles to reduce throat wear and increase barrel life. .277 bullet selection is improving.

    My plan for a 7mm build is to use a 338 Lapua as the parent case.
    "You will never know how much it cost my generation to preserve your freedom. I hope you make good use of it."
    ~ John Quincy Adams

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    MontanaRifleman:
    Where will you get 160 to 175 grain 270 bullets?

    Thanks
    SOTN
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  5. #5
    Member mainer_in_ak's Avatar
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    woodleigh even makes a 270 caliber 180 grainer.
    http://www.midwayusa.com/product/871...oint-box-of-50

  6. #6

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    Quote Originally Posted by Smitty of the North View Post
    MontanaRifleman:
    Where will you get 160 to 175 grain 270 bullets?

    Thanks
    SOTN
    Smitty,

    Guess you missed it in the OP...

    Matrix has 165's, 170's and 175's. Cutting Edge has a 165 that will need a tight twist.
    Berger has plans to make a 170 gr bullet but probably wont see that one for a couple of years.

    Nosler has a 160 partition, and that 180 Woodleigh looks interesting but I will be using the VLD type bullets.
    "You will never know how much it cost my generation to preserve your freedom. I hope you make good use of it."
    ~ John Quincy Adams

  7. #7
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    Congrates on your first wildcat MR...you sound like a proud parent! Let us know your reports from the bench. I have a hunch this will be an accurate creation for you...and a flat shooting laser beam. Regarding powder choices, you might put Retumbo in the line-up to try (just a thought). A friend of mine has a 7STW, and Retumbo is the only powder he could get to work well.

  8. #8

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    Quote Originally Posted by Doc View Post
    Congrates on your first wildcat MR...you sound like a proud parent! Let us know your reports from the bench. I have a hunch this will be an accurate creation for you...and a flat shooting laser beam. Regarding powder choices, you might put Retumbo in the line-up to try (just a thought). A friend of mine has a 7STW, and Retumbo is the only powder he could get to work well.
    Thank You Doc... I do feel like a proud parent

    Retumbo could be a player but it might be a little slow as an optimum powder for the heavier bullets. Using an overbore index by calculating the ratio of volume to bore area the 270 Montana comes in at about 1540. For comparison, the 300 RUM comes in at about 1440. The 7 STW is about 1450. Retumbo is an ideal powder for the 300 RUM with the heavier bullets, but with 210 gr bullets I am only at about 92% capacity. I'll be loading 230 Bergers with RL33 in my new RUM and I am expecting to max out with about 96% capacity. RL33 is a very slow powder in the 870 range. Retumbo is probably a more stable powder and i do like it for that but I'm not sure it will be best for the 270 Montana and the 165 gr bullets and up. It might do very well for 150 gr bullets with possible speeds in excess of 3500 fps.
    "You will never know how much it cost my generation to preserve your freedom. I hope you make good use of it."
    ~ John Quincy Adams

  9. #9

    Default

    Well today I borrowed some boolits and bushings from a friend. I sized a few case and seated some projectiles.

    From left to right...

    6.5 WSM 140 Berger VLD
    270 Montana 165 Matrix
    270 Montana 170 Matrix
    300 RUM 230 Berger Hybrid

    "You will never know how much it cost my generation to preserve your freedom. I hope you make good use of it."
    ~ John Quincy Adams

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