Heavy load for 300 WSM

Discussion in 'Reloading' started by brentc, Dec 12, 2011.

  1. brentc

    brentc Well-Known Member

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    Some info for those of you that like running heavy loads in the 300 WSM, I did some experimenting today with IMR 7828SSC and the Berger 230 OTM tactical Hybrid. I was intrigued with this combo because of the downrange energy. There simply is not a .308 hunting bullet on the market that can match the energy of this bullet even if flying 100 fps faster. Not even the 210 VLD at 2850.

    My rifle is a factory Winchester M70 Extreme Weather, 24" bbl, topped with a Zeiss Conquest 4.5-14x44.

    Load information: I used resized and trimmed Norma brass and CCI 200's for the test. I seated the bullets right at the lands, .000 jump which ends up at 3.310" COAL. BTW they still fit in the M70 magazine.

    I loaded 18 rounds ranging from 64 - 66 grains of 7828SSC and fired 3 shot groups to determine an OCW. the weather was a little drizzly today, and I ended up losing two chrono readings, but I still feel like I got good data. Here are the results.

    Load #1 64.0 grains IMR 7828SSC (Good group .35" all touching)
    #1 2650 fps
    #2 2624 fps
    #3 -------
    ES = 26 fps
    Ave = 2637 fps (baseline)

    Load #2 64.4 grains (Good group .55" in a cluster)
    #1 2677 fps
    #2 2656 fps
    #3 2645 fps
    ES = 32 fps
    Ave = 2659 fps (+22)

    Load #3 64.8 grains (scattered group 1.5")
    #1 2682 fps
    #2 2666 fps
    #3 ------
    ES = 16 fps
    Ave = 2674 fps (+15)

    Load #4 65.2 grains (tightening group .40" group - horizontal all touching)
    #1 2688 fps
    #2 2704 fps
    #3 2672 fps
    ES = 32 fps
    Ave = 2688 fps (+14)

    Load #5 65.6 grains (Tight group .30 with slight vertical)
    #1 2721 fps
    #2 2710 fps
    #3 2682 fps
    ES = 39 fps
    Ave = 2704 fps (+16)

    Load #6 66.0 grains (max load - slightly stiff bolt lift, not a horrible group - group was 2 shots on top of each other and the 3rd was about 1" to the left)
    #1 2693 fps
    #2 2688 fps
    #3 2704 fps
    ES = 16 fps
    Ave 2695 fps (-9)

    You can see the classic pressure curve leading up to the max load. It appears that the accuracy node is 65.4 or 65.5 grains. ES could improve a bit and it might with either of these charges. Overall, I think the test was a success and it opens up a bit more capability with the WSM. This bullet is about as close to wind proof as you'll find for a .30 cal and the down range energy is phenomenal. These are my results in my rifle. Load at your own risk.
     
    Last edited: Dec 12, 2011
  2. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

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    Great info thanks for sharing. I have an FN PBR in 300 wsm, any chance the M70 is a SA?
     

  3. brentc

    brentc Well-Known Member

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    It's the standard M70 WSM action. The WSM action is little bit longer than the standard SA.
     
    Last edited: Dec 12, 2011