7mm VLD analysis

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by BryanLitz, Sep 30, 2008.

  1. BryanLitz

    BryanLitz <b>Official LRH Sponsor</b>

    Messages:
    633
    Joined:
    Mar 8, 2007
    Fellow shooters,
    I've added some new material to my site. It's a two part series about the BC test results, stability characteristics, and comparative performance analysis of the 7mm 168 and 180 grain VLD's. Effects of meplat pointing/trimming are addressed. The comparison illustrates the difference in wind drift, and the impact on score assuming given wind estimation uncertainties using the standard NRA LR Prone target. Although the analysis is geared towards known distance (KD) target shooting, the raw data is relevant to anyone who shoots these bullets.
    Homepage of Bryan Litz - A Bravenet.com Hosted Site
    Enjoy,
    -Bryan
     
  2. phorwath

    phorwath Well-Known Member

    Messages:
    4,896
    Joined:
    Apr 4, 2005
    Wow! I'm using the Berger 168 VLD for LRH and just last weekend I shot at both 300 yds and 990 yds in the effort to establish the field performance BC out of my rifle. I came up with a G1 BC of 0.615 in order to best match my trajectory with a MV = 3080 fps and 990 yd target velocity of ~ 1700 fps, at an elevation of 275'. It look's like your test averaged a G1 BC of 0.617 lb/in2 for that bullet. Probably just a fluke that my BC was so close to the average that you determined. Especially since I only fired two shots @ 990 yds. That was my initial testing out to 900+ yds. I'll tweek my drop chart and shoot again in a confidence building effort to help confirm that my BC is really a close match to my bullet trajectory.

    Neat stuff. Close to going over my head but appreciate your post and sharing your research. There's quite a few folks using the Bergers for LRH and others will be able to take advantage of your derived BC information also.

    Paul
     

  3. AJ Peacock

    AJ Peacock Well-Known Member

    Messages:
    2,229
    Joined:
    Oct 7, 2005
    Excellent articles. Absolutely great!

    Would love to see the Meplat article updated with the 300gr .338 Sierra Matchking.

    Also, there is an article/discussion on this site about scope alignment that would dovetail nicely into your Coriolis/gyroscopic drift article.

    Nicely done!

    AJ
     
  4. royinidaho

    royinidaho Writers Guild

    Messages:
    8,853
    Joined:
    Jan 20, 2004
    Excellent Articles!

    a very good read, especially for 'this' novice.

    Thanks for your effort.
     
  5. landcbeitner

    landcbeitner Well-Known Member

    Messages:
    421
    Joined:
    Jan 13, 2008
    Those articles are great! Thanks for sharing your knowlege. I've been using the multi-BC option in my X-ball to get my actuall drop to match. Your info may help me match better. Thanks once again!
     
  6. jmden

    jmden Well-Known Member

    Messages:
    2,725
    Joined:
    Nov 2, 2003
    Interesting analysis. Thanks for sharing.
     
  7. JeffVN

    JeffVN Well-Known Member

    Messages:
    619
    Joined:
    Mar 19, 2004
    Interesting read.

    JEffVN