Ballistic Calculation Help!

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Guest, Aug 18, 2004.

  1. Guest

    Guest Guest

    I would appreciate any BC numbers you can help me with; up to 1000 yds. for my .264 WinMag, with a 26" heavy barrel, 1-9 twist, 140gr psp at 2945 fps, or 140 xlc at 2965 fps. The centerline of my scope is 1.757" above the centerline of my bore. Thanks for your help, and please let me know if you need any additional data. Thanks!

    [ 08-19-2004: Message edited by: nighthunter264winmag ]
     
  2. Guest

    Guest Guest

    I would also appreciate any suggestions on a ballistics program that has served them well. Thanks in advance for your help!!!
     
  3. orwapitihunter

    orwapitihunter Well-Known Member

    Messages:
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    Jan 4, 2004
    Nighthunter264
    Have you used JBM's site? You should check it out. Now if I could just get the G functions and factory vs real world BC's figured out I would be set.
    http://www.eskimo.com/~jbm/

    Thanks for sharing your knowledge JBM.
     
  4. Guest

    Guest Guest

    Birdshooter,
    Thanks for the advice. I'll check it out right now!
     
  5. Jeff In TX

    Jeff In TX Well-Known Member

    Messages:
    408
    Joined:
    Aug 10, 2003
    Birdshooter,

    JBM's online program is fantastic, not to mention it is free.

    I use the RSI Shooting lab, which is the most powerful program on the market and has many more capabilities of what the JBM on line program currently offers. Don't get me wrong; I really like the JBM online program and used his 90’s version JBM OT pc program until he stop selling and supporting it.

    One of the RSI program features that I really use is the Estimate Drag Function. This feature allows you to take your actual range data and directly compare it to all of the different drag models. This way you can pick the best drag model that fits your bullet/load and actual range data.

    Then you don't have to guess if you should use a GL, G1, G5, G6 or G7 drag model.

    Hope it helps.
     
  6. Guest

    Guest Guest

    Thanks for the post Jeff! I've spent a lot of precision time in building this thing and I don't want to learn from making mistakes; especially when I can talk to guys like ya'll (A Texas word). I always appreciate any advice that you have in my preparation to do some serious long distance shooting!
    Mike
     
  7. Jeff In TX

    Jeff In TX Well-Known Member

    Messages:
    408
    Joined:
    Aug 10, 2003
    nighthunter264winmag,

    Not sure of your exact requirements of your current project. Whether it's hunting, bench, tactical rifle or what you are really trying to build and what your actual goals are with it.

    This is one of those projects where you can spend a little or a lot depending on what you want.

    If you're going to shoot long range, you need at least two different additional items, a good Chronograph and ballistic program. These two items can make your life much simpler.

    I would recommend the RSI Shooting Lab ballistic software and the CED millennium Chronograph. A third item for the extremely serious long distance shooter pressure trace software. I'm not that die-hard yet.

    I've attached the link to the RSI shooting software for you to browse. But do yourself a favor first and call Jim Ristow at RSI on his toll free number. This mans knowledge is unreal. Jim got me started in ballistics’ about 10 years ago. He understands this stuff better than anyone I've ever talked with. When I get stuck on a problem and I can't figure it out, Jim gets me through it. Mind you, he's sharp and sometimes I have to real him in and get him to talk in language I can understand.

    I use two of his CED chronographs though he tells me how unnecessary it is. He actually tried to talk me out of my second unit. But, I've chronograph my loads at the muzzel and out to 700 yards using the two units. With his ballistic program I know exactly what my load will do out to a 1000 yards.

    After I had my muzzel, 100, 200, 300-yard average velocities, I was able to work with his RSI ballistic lab and it predicted my 4,5,6 and 700 yard velocities dead on +- 2 fps. that was the farthest I could shoot and not worry about shooting the bullet sensors on the chronograph. At 1000 yards I was right on, even when the atmospheric contitions changed and temps were rising to over a 100 degrees like we get here in TX. I changed atmospheric conditions on the program and the RSI programmed tracked exactly.

    If you want to email me with your number, I'll be glad to give you a call and we can talk.

    Best of luck.

    JeffRSI Shooting Lab web site
     
  8. Guest

    Guest Guest

    Hi Jeff,
    I really appreciate the info. I built this rifle for long distance hunting; something I've wanted to do for a very long time. I will definitely take your advice, and will also send you a pm with my office number.
     
  9. orwapitihunter

    orwapitihunter Well-Known Member

    Messages:
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    Joined:
    Jan 4, 2004
    Jeff thanks for the tip. I'll look into it also. I usually shoot the various distances and then try and match it with the computer to look for possible errors at the range. Kind of a back and forth process.