7mm Ultra Mag...180 Berger...Need Data

Discussion in 'Reloading' started by william70d, Sep 6, 2010.

  1. william70d

    william70d Member

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    I have been long range hunting and shooting for years. I just picked up a remington sendero in 7mm Ultra mag. I bought this gun so I could take advantage of the 180 Berger bullet. I have recieved the data from berger and loaded the max of

    86 grains of Retumbo with an OAL of 3.65.

    chronographed muzzle velocity average of 2930 of 5 shots

    .5 Moa groups @ 100yds

    The claimed velocity from berger out of an 24in barrel is around 3050. So my 26in barreled sendero should be a tad faster than that. I know that reloading datas claimed velocity is never close to actual chronographed muzzle velocity but I feel that there should be alot more speed to be had out of this case. With the was the bullet is seated....which is way down in there to get it to feed out of the magazine....there is plenty of room for more fuel. I was wondering if anyone on this sight has loaded this round and if there is any more data for the 180 berger. I would like to see it over 3000 and have found rumors or claims on the web of up to 3200 fps, but of course no data and the ones making the claim probally have never even heared of a chrono. I know this round has a serious overbore problem which could result in increased case pressures so I really dont want to get to wild with going over bergers max recomendation without someone else tryin it first..:D

    any info will be appreciated.

    thanks...David
     
  2. coyotezapper

    coyotezapper Well-Known Member

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    Try Hodgdon US 869. It is excellent with heavy bullets for caliber. I would start at about 99 grains and work up slowly.
     

  3. william70d

    william70d Member

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    where did you come up with the 99 grains?
     
  4. davewilson

    davewilson Well-Known Member

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    i had a 7rum and shot the 180 Bergers at 3250. this was a 30" barrel, 3 groove, 7 twist. used 100 gr of 872 powder. i always felt that Retumbo would give me more velocity because others did. walk your powder charge up until you get a sticky bolt then back off about 3 gr, that would be your max with that combo.
    i didn't have the cartridge long, i rebarreled it to an edge and never looked back.
     
  5. william70d

    william70d Member

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    I will try working the loads up with retumbo. As long as the accuracy stays? I will keep everyone posted
     
  6. coyotezapper

    coyotezapper Well-Known Member

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    Hodgdon
     
  7. william70d

    william70d Member

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    so you going with a middle of the road powder charge for a 175 grain bullet. Is this safe?

    175 grain sft sp
    min 95 grains, max 102 grains

    Is data like this typically used?
    Thanks
     
  8. coyotezapper

    coyotezapper Well-Known Member

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    You can use the data for the 175 if you want stopping just short of max. Hodgdon is very conservative in their data. I very rarely get the same velocities with what they list in their data. Hodgdon does list pressures and pressure equals velocity. I load to their velocity/pressures and ignore their max charge recommendations. I have never had a problem doing it this way. You do need a chronograph though. US 869 is a ball powder so you will see pressure signs sooner than you would with stick powder so once you get past max charges go in small .2-.3 grain increments. US 869 is perfect for the 7mm rum.
     
  9. strobes

    strobes Member

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    Cartrige AOL is critical for accuracy and pressure.
    I'd suggest to find max cartrige AOL for your rifle and work on the load than.​

    for reference:​
    Max pressure for this cartrige is 450 MPa.
    87.8Gr retumbo will push calculated pressure to 450MPa and velocity to 2957 FPS based on AOL listed below​
    Bullet : .284, 180, Berger VLD
    Cartridge O.A.L. L6: 3.600 inch or 91.44 mm
    Barrel Length : 26.0 inch or 660.4 mm​
     
    Last edited: Sep 9, 2010
  10. william70d

    william70d Member

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    well currently my load of 86 grains of retumbo and an oal of 3.650 which is the max for feeding out of the mag. I yield a chronographed 5 shot average of 2930 fps. I think I need to load some with us869 for comparison. Thanks for all the input.
     
  11. strobes

    strobes Member

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    you can see that in the load you have you are close to max pressure.
    Also second screenshot shows calculated absolute max load for US869.just for your references.
    Also see the difference in ballistics between 2920 and 3000fps - not mach
    but to reach 3000 you may compromise safety and make barrel life sorter.
    Just my personal opinion.....

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

     
  12. coyotezapper

    coyotezapper Well-Known Member

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    Let me clarify a point about pressure. When it comes to OAL I never jam bullets in my hunting rifles. I load to fit magazine and tweak load from there. I have never had a problem getting a bullet to shoot well doing this. The Quickload data is interesting but it is just a computer prediction. As with different barrels sometimes it is close with a specific powder and sometimes it is not. I have found Quickloads accuracy to be about 80% which is pretty good but I don't use it anymore. I first purchased it about 2001 but updates were always slow with new powder. I have had Berger send me load data worked up with Quickload and it is very conservative. I have had no problems going higher in most cases. With warmer loads I will verify pressures with Oehler 43 just to be safe.
     
  13. strobes

    strobes Member

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    Yes I agree that Quickload may be 15-20% off, thought in my experiens it's usually less that 10%. But bullistics calculation are accurate and show insignificant advantages having 3000 FPS load vs. 2920FPS.

    And as been sad - less sterss on barrel, cartriges, better safety. just an opinion...
     
  14. william70d

    william70d Member

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    thanks for all the info...I really appreciate it