Berger Bullets' Move To The G7 Standard BC By Bryan Litz

Discussion in 'Technical Articles - Discussion' started by ADMIN, Jul 15, 2009.

  1. ADMIN

    ADMIN Administrator

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    This is a thread for discussion of the article, Berger Bullets' Move To The G7 Standard BC , By Bryan Litz. Here you can ask questions or make comments about the article.
     

  2. birdrl

    birdrl Member

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    A very good article. Explained a lot of things I did not understand. Thank you.
     

  3. ODAVID

    ODAVID Well-Known Member

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    Excellent article Very informative. I am developing a Balistic table based on Actual range results showing the POI at 100-200-400-600-800-1000 yards. The POI is consistent for the ranges but the table does not corelate. I feel this is because of the Bullet BC value.

    Can you share with me the G7 BC for the Berger 168 gr 7mm Hunting bullet leaving the muzzle at 3300fps????

    Can you also share with me the G7 BC for Nosler Accubond bullet 160 grain leaving the muzzle at 3220 fps??

    I assume these G7 BC will be the same throughout the entire range I shoot??

    How much of a varible is the Fps for the Balistic table????


    Thank you so much
     
  4. jonoMT

    jonoMT Well-Known Member

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    I had observed on another thread that the G7 BC varies much less than G1. Thanks for the explanation why. (If I am correct, that is because the G7 bullet model is much more similar to the shape of modern projectiles such as the VLDs).

    To be honest, I hadn't given much consideration to trying yet another bullet brand but I'm impressed with Berger. I've got 6 hours of range time Saturday so am going to load some 168 or 175s...if I can find some locally!
     
  5. ctressler

    ctressler Member

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    Great article and thank you for the links to the software
     
  6. bubbinator

    bubbinator New Member

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    I recently read an article in Shooting Times or Guns & Ammo on this same subject. It stated that ballistic coeffients were calculated on values based on the GI .50 Cal machine gun round. That round was given a BC of 1.000 and all others were compared to that. In reviewing the BCs given to various bullets, for example a 220gr. .30 roundnose projectile VS a 175gr. HPBT Match projectile, that system of comparisons makes it easy for me, at least, to visulalise the BC values. Is there any substance to that comparison? Thanks for your input, enjoyed your article a lot.
     
  7. Eaglet

    Eaglet Well-Known Member

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    True!!!,

    Will Berger print on their boxes the new G7 BC only or will they

    start out in a wiser manner like printing the G1 and G7 on their boxes

    for some time until more folks get educated on the matter. It's indeed

    a daring step though in the right direction. I would Print Both of them

    on the ammo boxes to start the introduction. There's lots of folks that don't

    even know what G7 is.
     
  8. royinidaho

    royinidaho Writers Guild

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    This "magazine" is getting quite good.

    It's nice to be around the fire when the paradigm changes.lightbulb

    I've done some drop chart development that took a bit of fudging w/G7 bc option to get things right. Now I know why.

    Good article in a great magazine.
     
  9. BryanLitz

    BryanLitz <b>Official LRH Sponsor</b>

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    Eaglet,
    We'll be printing both G1 and G7 on the labels for a while. As you said, introducing this new data is daring enough, to immediately abandon the old familiar safety net would be too abrupt. These things take time. Thanks to forums like this, the information can flow quickly and expedite the 'wholesale' switch to something better.
    -Bryan
     
  10. Horsemen

    Horsemen Active Member

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    Bryan, very good article! You have struck my need to know more nerve. So I ordered your book and will read it more than once to let it all sink in. After soaking up as much as possible, I Will need some soft wear to apply what I have learned. This is were the chooses get confusing. I have done some research, on most of the popular soft wear programs.With the exception of JBM,(witch is web based) None of these products state witch BC standard they use. Is there a way to list the soft wear that uses all of the BC standards?

    Regards Mike.
     
  11. Forester

    Forester Well-Known Member

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    Yet another reason reason to choose Berger, and why they are my go to brand anymore. A gun has to first show it just won't shoot Bergers for me to go fool with another brand.

    Bryan: Great article and I will order the book soon. In the meantime is there any chance you could post a list of the bullets included in the book? Not the BCs of course just a list so we know what is included?
     
  12. BryanLitz

    BryanLitz <b>Official LRH Sponsor</b>

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    Mike,
    Thanks for the compliments and for ordering the book.
    As far as what software programs use G7, well, the one that comes with my book does. Also, some of the programs that are free for download from the JBM site use G7. AlBal is one I remember in particular. If you want to pay for a more inclusive program, I know LoadBase and the RSI software programs have an option for G7 as well. I'm sure there's others but I don't have them all on top of my head. It would be a good idea to compile a list.

    Forester,
    The question was asked on another thread, you can see the list of bullets here:
    http://www.longrangehunting.com/forums/f19/new-book-applied-ballistics-long-range-shooting-43573/

    It's post #5 in the thread.

    Take care guys,
    -Bryan
     
  13. Kevin Thomas

    Kevin Thomas Well-Known Member

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    Hi Bryan,

    Do have to take exception to one portion of this piece; the comment about the industry utilizing the G1 drag model simply because it results in the highest numerical values. In other words, a marketing ploy. As long as we have every one's attention here, I'd like to reaffirm the fact that the universal use of the G1 drag model is one of expediancy (okay, laziness) , not a marketing strategy. Until relatively recently, very few shooters had any concept or underestanding of BC. Sadly, based on the Shooting Times comments about the BCs being based the .50 BMG round, many gunwriters still don't. It was nothing more than a quick and lazy way for manufacturers to compare a diverse spectrum of bullets with the minimal amount of work. What is called for here is that each bullet be used with the proper drag model appropriate to that bullet, be it a G1, G2, G5, GL or the G7 or any of several others. As you know (and others should understand), the G1 is not an appropriate drag model for the .30 cal 170 FN for a .30-30. Neither is a G7. I don't have Lowery's text in front of me here, but there is a drag model specific to flat-based, flat (or blunt) nosed projectiles. That's what should be used, but for a 75 yard shot from an iron sighted M94, does it really make a huge difference? Most of the Lyman pistol designs should properly use the GL model, but like the M94 example, we're talking about some pretty finely split hairs here.

    Berger has an advantage in this field, in that the vast majority of the line is appropriate to the G7 model. A bit more difficult for a company that produces a range of round noses, flat noses, hollow point pistol bullets, etc.. In that respect, Berger is the perfect company to step up to this particular plate, and I'm truly glad to see you do it here. The time is right; we now have the range of computer programs that make this subject more accessable to a wider range of shooters than ever before. Forums like this allow for a great exchange of info between (frankly) a more advanced group of shooters, than presented by the mainstream gun rags and their more generalized audiences.

    I think even with the aforementioned ballistics programs, we're still a long ways off from listing and using the correct drag model/table for each type of bullet. Still, the thorough explanation of the G7, and its applicability to the streamlined BT bullets used in Long Range competition is a major step forward in this regard, and I applaud you and Berger for daring to enter the fray. It's a start, and a damned good one.

    Keep it up, Bryan, you're performing a real service here!
     
  14. jonoMT

    jonoMT Well-Known Member

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    One of the first things that should be made apparent to anyone trying out a ballistics calculator is to select the proper drag model. I don't know if a different drag model would provide a similar lack of BC deviation for a non-VLD that the G7 model does for VLDs, but it's all I'm using now for bullets that fit that model.