300 wm load development

Discussion in 'Reloading' started by gspman, May 21, 2012.

  1. gspman

    gspman Well-Known Member

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    I am a little miffed at my measured velocity differences during my load development phase.
    I have sorted all my cases (R-P brass),I have 24 3x reloaded brass. All weight within a half gn of each other.
    I have sorted my accubonds so they are all the same weight exactly.
    Tumbled, then ultrasonic cleaned prior to loading.
    All brass sized to exactly the same dimensions. with the exception a some slight variance in case neck length.+/- .001.
    This batch of cases was annealed prior to this loading.
    I have each charge measured exactly.
    Used rcbs charge master for all weight measurements and powder throwing.
    Primer pockets all uniformed.
    I got my best group with 74gn H4831sc measure at 2960, 3011, 2932.
    3 in the x, perfect clover leaf (.4x in.)
    How can i get this group with the variation in measured velocity, what can i change in my procedure to tighten this up some. bullet seated .010 off the lands.
    I am scratching my head here?
     
  2. MagnumManiac

    MagnumManiac Well-Known Member

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    Taking a reading of only 3 shots is a waste of time, it tells you nothing.

    If you take an average of 10 shots, then get your ES, SD and Average velocity, you will have a far better idea of what's going on with your load. Once you know these factors, you can play with seating depth to 'fine tune' your load, or dabble with .3gr above and below your best powder charge to find the accuracy node. 74gr's of H4831 sounds a little soft to me, if you are using 180gr pills. You should be able to get 3100fps with a 180gr pill.

    What was the max load grouping like?
    Have you tried RE22 or RE25?

    I look for a low SD in my loads, but as many shooters are aware, a low SD does not always give the best accuracy.
    I too shoot a 300WM, and I look for a load that is near or at max, it gives me the best accuracy and I like to have a heavily compressed load with at least 100% fill capacity.
    I really like RE25 with either 180gr AB's or 200gr AB's. Remington brass is fine if you take the time to prep it well.

    Cheers.
    gun)
     

  3. Broz

    Broz Well-Known Member

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    These are the kind of results I see when the chronograph is too close to the muzzle of the rifle. The muzzle blast impacts the sky screens vibrating the chrono giving irratic readings. Shoot some more with the chroograph at least 18 ft from the muzzle and on as stable of a mount as possible. If you were like at 10 feet I woul bet on this being your issue.

    Jeff
     
  4. gspman

    gspman Well-Known Member

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    I was originally going to use rl22, but was told that its not as temperature stable. Since this will be a hunting round in the northern climate. stability is a factor.

    My chrony is as far away from the muzzle as the the remote display will allow 10-12 feet i never measured its length
     
  5. RTK

    RTK Well-Known Member

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    May 9, 2012
    What do you feel a good ES and SD are??
     
  6. Broz

    Broz Well-Known Member

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    Well your low to high is 79 feet per second. That is huge and I am betting it is not the load. I would try getting farther back.

    Jeff
     
  7. jsthntn247

    jsthntn247 Well-Known Member

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    I am shooting a 180gr load tomorrow with 80-83 grains of H-1000 out of a 24" tube, I will report back and let you know how it came out. I always set my chrony 15 feet from muzzle so I don't get powder interference. Also If your ES is still high, load 5 shots with different types of Mag and non Mag primers and see if your es goes down. Seating closer to the lands also might help with es.