Trouble developing load

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 7mmboy, Nov 20, 2013.

  1. 7mmboy

    7mmboy Member

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    G'day all,
    I am shooting a 7mm dakota with a benchmark 28" abs carbon wrapped barrel, I have tried 180 smk, 180 berger hybrids,180 berger vld and 162a-max with ar2225 (retumbo)and have struggled to get a load that would print less than 3/4 inch at 100 yards, I have tested different seating depths with all of the above and seem to be chasing my tail with this , I do a lot of shooting and my hunting rifle has printed me .3" at 100 30/06 ai. What could be the problem.
    Regards
    7mmboy
     
  2. BountyHunter

    BountyHunter Writers Guild

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    Start with confirming all screws are tight and action is torqued.

    Test groups with 5 lb variance on torque

    Try H1000 also
     

  3. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    What's your twist?? Some 7mm customs have 10" twists and are more suited to bullets in the 140-150 grain range. If you are a 9" twist or so I'd look at action bedding/ barrel floating, action screw torque, shooting technique/ bagging etc., scope repeatability, barrel crown, chamber dimensions, action squareness, and bases/rings to start with. You likely only have an issue with one of the above, so I just tossed them all out as possible reasons.
    Also, some barrels simply don't like certain bullets. I've had a few barrels settle down when you switch bullet brands or switch from single base to double base powder. Also work on bullet seating depth adjustments with your best loads. The last thing I'm thinking of is some barrels just don't shoot as well as they "should" no matter what you do. Even expensive barrels occasionally have this problem; I hope your barrel isn't one of them.
     
  4. J E Custom

    J E Custom Well-Known Member

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    I would recommend using a chronograph with different powders and primers to find a good load,
    then with that good load (I call a good load anything less than a SD of 10 ft/sec).try different bullets of the same weight. Once the best and load are found them try seating depths for the best accuracy.

    Different rifles like different loads and different bullets. The chronograph will save time and eliminate poor/bad loads. While working up loads only change one component at a time.

    I use lots of Retumbo but it does not work on some cartridges/rifle combinations.

    You may already know this but it is the way I do it and it saves many rounds for me.

    J E CUSTOM
     
  5. deadlift

    deadlift Official LRH Sponsor

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    Which primer are you using? On my 7mm dakota I run CCI BR2's with 77.6grs of retumbo and the 190 matrix's. Currently we have 4 rifle running this combo with better than .5 moa accuracy. There are a couple thing to try, thats a big, long bullet shoot it at 300 and 600, then see where you are. I have found that carbon wraps like to have the bipod loaded while shooting. How are you shooting? Prone? bench? Both? That barrel will be a 9" twist so you shouldn't have any problem with the 180's. How often are you cleaning? What jump/jam are you using on the bullets?
    Chris
    Benchmark Barrels
     
  6. 7mmboy

    7mmboy Member

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    I am using the cci 250 primer.. I am shooting prone with atlas bipod.i clean every 25-30 rounds and have tried various seating depths. In and off the lands
     
  7. deadidarren

    deadidarren Well-Known Member

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    try grouping at 200yards
     
  8. 7mmboy

    7mmboy Member

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    Dead lift what do you mean by having the bipod loaded while shooting?
    I will try it at 400 in the next couple of days.
    Regards
    7mmboy
     
  9. deadlift

    deadlift Official LRH Sponsor

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    Push into the bipod when firing prone. When you do that it can dampen harmonics and limit the recoil impulse as well as any hop. The key is to stay consistent with you loading. Free recoil is when you only support the buttstock and allow the front of the weapon to move with recoil.
     
  10. alaska

    alaska Well-Known Member

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    Check your twist

    To shoot the 180 VLD you need a slower twist

    Reloader 25 is a good powder