SLOW VELOCITY 270WSM - 7mm.RM

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by wheelgunner, Jan 14, 2009.

  1. wheelgunner

    wheelgunner Active Member

    Messages:
    32
    Joined:
    Sep 29, 2008
    Hi guys,

    i have a "velocity" problem with my more accurate reloads.
    I made a lot of test, to find the best load with the Nosler Accubonds, in my rifles, TikkaT3.lamin/stainless 7mm.RM and Sako75 sinth/stainless .270WSM.
    The best accuracy loads i have found are theese:

    - 7mm.RM (TikkaT3) - 24" barrel
    Accubond 140 grs. x 66.00 H4831
    Aol = 3,290"
    brass = Norma
    primer = Fed GM215M
    Vo = 2.850 fps.
    distance = 185 yds.
    group = 0.825" 5 rounds (with 1st. round - barrel clean)
    group = 0.472" (the others 4 rounds)

    - .270WSM (Sako75) - 24" barrel
    Accubond 130 grs. x 65.00 H4831
    Aol = 2,870"
    brass = Remington
    primer = CCI250M
    Vo = 2.965 fps.
    distance = 185 yds.
    group = 0.787" 4 rounds
    group = 0.551" first 3 shots

    ...... why my loads don't go over 3.000 fps / 7RM and over 3.100 / .270WSM ? ... i really don't understand ! ...

    I would like to know your point of view about theese poor energy loads, consulting the Hodgon data manual (on line), i should stay about 1grs./1.5grs. less the max charge ..... but i can't understand theese results.
    i really don't want use a magnum caliber .... with the result of 7.08 or a .270w ... HELP ME ... :rolleyes:

    (The strange distance, 185 yds. , it is the max i can in my pistol-shooting-range)

    Thank you so much for your help.

    Luca
     

  2. WyomingShooter

    WyomingShooter Well-Known Member

    Messages:
    51
    Joined:
    Nov 22, 2007
    These two are excellentand very accurate cartridges but are not known as speed burners. If you want speed you should get the 270 weatherby mag, 7mm wby or a 7mm stw.
     

  3. johnnyk

    johnnyk Well-Known Member

    Messages:
    1,728
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    Dec 24, 2001
    wheelgunner,
    You're right in being concerned. Both your 7RM and 270WSM should be spitting those selected projectiles at over 3200fps. I have a 7RM, it has a 26" tube and I'm getting 3200 + with IMR4350 and 150gn Ballistic Tips. I just traded my 270WSM but I was getting over 3300fps with 130gn NBT's. I suggest you try a different powder. IMR4350, 4831, 7828, H4350, Retumbo, H1000, RL22, AA3100, Hunter, Big Game all come to mind. All are good powders for these two rounds and produce better velocity than you're getting.
    Not sure where or how you're getting your velocity. You may be using a bump chronograph. The only thing the two rifles/cartridges have in common is the powder and chrono (I assume). Let us know. JohnnyK.
     
    Last edited: Jan 14, 2009
  4. Beanfieldrifle

    Beanfieldrifle Member

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    23
    Joined:
    Dec 2, 2005
    At what range is the Crono and are you sure it is not the Crono that is just reading slow?

    I have played with the same 270WSM load and saw around 3100 FPS for the exact same powder and primer combo using the same powder amount.

    H4831 is a good powder for the 270WSM. R19 or H1000 (which really fills the case) has been better for me.
     
  5. Shortmagman

    Shortmagman Well-Known Member

    Messages:
    447
    Joined:
    Feb 22, 2008
    I reload for both my 7mm Rem Mag(Ruger 77 Mark II) and my 270WSM(Winchester Model 70) and have had to slowly work up the powder charge above what is listed to get the velocity that is given in the reloading manuals. I think it is because both my guns have a long throat and it take more powder to achieve the stated velocity.

    I think that Johnnyk is correct. I have gotten my top velocities using Magpro or RL-22 in both guns. I load RL-22 because I get good velocity and better accuracy with it than with Magpro.

    So my suggestion is to get some different powder and slowly and carefully work up the load, using your chronograph as guide. Watch for any pressue signs such as a sticky bolt .You should be able to match your goal.

    I have gotten over 3200 ft/sec from both guns using 140 grain bullets and the correct amout of powder(both my guns have 24 inch barrels). With RL-22 I am using more than the manuals state as max.

    So be careful and work up slowly, at .5 grains at a time.
     
  6. wheelgunner

    wheelgunner Active Member

    Messages:
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    Sep 29, 2008
    Thank you to everybody for yours repplies.
    I'm just come back from an hunting week-end in Hungheria (roe-deer), and the loads we are talking have stopped 4 roe-deers from 140 mt. to 205 mt. with the accuracy i was tested.

    Regarding the repplie about the chrono distance (from the muzzle), it's about 3/4 meters .... and i will try again with another chrono (from a friend) if there will be differences.

    Now i would like to try 67.00 - 68.00 for the 7mm.RM and 67.00 for the .270WSM (66.00 just tested, but the groups was a "buckshot-group").

    i'll let you know .... thank you again !

    Luca