New barrel grouping issue - Please Help

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Jinx, Apr 29, 2012.

  1. Jinx

    Jinx Well-Known Member

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    Apr 21, 2008
    Hello

    My friend recently fitted a new 28 inch barrel to his 243, 1:10 twist. He usually reloads and the previous barrel shot sub MoA groups at 200 yards with a 24 inch barrel. The bullets he was using was 87 V MAx with winchester brass. The rifle is fitted with a Leupold VX3.

    He broke in the barrel by cleaning the barrel after each shot and letting it cool properly. He shot 20 bullets through the barrel after he decided to site it in. The groupings are sporadic at best. He would group 3 shots and then it would start going everywhere.

    The problems he has considered are the following:

    The gunsmith may made a mistake with the fitting of the barrel and it will be taken in shortly.

    Problem with brass which will be replaced with Norma brass.

    What other problems can there be?

    He is a good shot and quite meticulous when reloading. Can the bullets be too light or too heavy for the twist?

    Any suggestions will be highly appreciated.
     
  2. KRP

    KRP Well-Known Member

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    Dec 25, 2007
    All the basics have been checked? Rings, base, scope, bedding?
     

  3. Jinx-)

    Jinx-) Well-Known Member

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    Aug 23, 2009
    never had luck with 87gr V-max bullets in my 6BR that's 1:8 twist... But 90gr Berger make one hole groups, must be something about them V-max my barrel doesn't like ;-) and winchester brass common ;-) get some lapua or norma brass if you after precision shooting.
     
  4. Trickymissfit

    Trickymissfit Well-Known Member

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    Jun 11, 2010
    try this: Run a very tight patch thru the barrel. Marking all the tight spots and loose spots in there. If the last four inches are loose, then you need to either cut the barrel back to where it's tight on exiting the barrel, or plan of doing a bore lap job. I think it was Calfee that said that a 30" blank was only good for 26" at the most. Did they install a muzzel brake at the end of the barrel or do any machining that involved the last six inches of barrel? Lastly, I'd remove the action and have a good look at the recoil lug and where it seats. If it looks good then reinstally the action and use a good torque wrench. Start out with 35 in. lb. and adjust the torque from there. But don't go much over 50 in.lb.
    gary
     
  5. mrbigtexan

    mrbigtexan Well-Known Member

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    Oct 8, 2009
    all barrels like different bullets, or different powder charges. what was the twist on the old barrel? has he tried seating the bullets at different lengths? i am now a firm believer in finding the "sweet spot" before finding the correct powder or powder charge. with a different length barrel i believe he will just have to start over finding a load that it likes.
     
  6. rem.xp100

    rem.xp100 Active Member

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    Mar 30, 2005
    Lots of good information in posts above - also don't neglect checking the crown.

    Dan
     
  7. Trickymissfit

    Trickymissfit Well-Known Member

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    Normally a bad crown will push a bullet in one direction only unless it's bad all the way around. It's not all that common for a bad crown to be bad all the way around, but I saw one factory barrel that was bad 360 degrees once. That is possible for sure, and easy to spot with a strong light and a magnifing glass.
    gary