Question about Wildcat bullets--BCs

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Derek M., Mar 16, 2007.

  1. Derek M.

    Derek M. Well-Known Member

    Messages:
    2,417
    Joined:
    Jul 12, 2004
    I know that the BC of a bullet is dependent on several factors, but given an average velocity, does anyone know the approximate BCs of Richard Grave's .277 hunting bullets? Specifically, the ULD RBBT style in 130, 140, 150, 160, and 169.5?
     
  2. bailey1474

    bailey1474 <strong>SPONSOR</strong>

    Messages:
    1,922
    Joined:
    Dec 7, 2004
    I can tell you that Lerch and used .740 for the 169.5s and it was very close to our actual drops. Requires around 14-16 MOA @ 1000 yds out of our 270 AMs.
     

  3. NYLES

    NYLES Well-Known Member

    Messages:
    773
    Joined:
    Dec 18, 2006
    I didnt do it! /ubbthreads/images/graemlins/grin.gif
     
  4. britz

    britz Well-Known Member

    Messages:
    1,217
    Joined:
    Mar 11, 2007
    Here is a website that will allow you to calculate the BC from conographing your shot two different known distances. I checked it just now against my Nosler number 4 manual and a couple of guns and it seems to work. http://www.eskimo.com/~jbm/calculations/bcv/bcv.html" good luck,
    britz
     
  5. 1kstr

    1kstr Well-Known Member

    Messages:
    221
    Joined:
    Dec 20, 2006
    Noticed if you click on britz' link you will have to delete the "m" in front of http:

    britz - maybe you could edit that quick.

    1kstr
     
  6. britz

    britz Well-Known Member

    Messages:
    1,217
    Joined:
    Mar 11, 2007
    gotter fixed, sorry about the mistake, maybe I should double check my work lol!
     
  7. lerch

    lerch <strong>SPONSOR</strong>

    Messages:
    1,497
    Joined:
    Nov 15, 2004
    BJ is right, .740 on the 169.5 ULD worked perfect for me out to 1500yds or more.

    one hell of a bullet!!!!!!!!!!!!!

    steve
     
  8. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    I also use 0.740 BC for the 169.5 gr ULD RBBT. Don;t mess with the lighter ones, no reason to for what I use the 270 for.

    This BC works very well for muzzle velocities from 3200 to 3400 fps at 3300 ft altitude. I have tested out to 2200 yards with this bullet and from dial up figures this BC holds pretty damn close out to that range so I figure its a good average BC for out to extreme range.

    Do not know if the BC drops with lower muzzle velocities but I doubt that it does much.

    Again, these BC numbers are what I need to put into my Exbal program to get the predicted bullet flight to match actual bullet flight.

    It may not be the pure scientific BC but its what I have to use if I want to hit what I am shooting at at long range.

    Kirby Allen(50)
     
  9. BLASERMAN

    BLASERMAN Well-Known Member

    Messages:
    281
    Joined:
    Apr 9, 2005
    I learned alot on here so far , Time to school me some more .
    Am trying Richards 150 RBBT ULD's in my 7 mm STW normaly I shoot swift scircco 150's at Taken data loads of 3400fps.
    I don't have a Crono ,( next piece to buy).The Swift has a BC of .515 are Richards that much higher BC. In the 600 range or 700 . In the program in this post how do you know What the G factor is .
     
  10. britz

    britz Well-Known Member

    Messages:
    1,217
    Joined:
    Mar 11, 2007
    Whenever I use JBM to calculate tradjectories, I honestly just ignore it and go w/ G1, seems to work. I know this isnt' the answer that you were looking for, but it's all I got lol! Maybe someone a little more knowledgeable about ballistics can tell us!
     
  11. Derek M.

    Derek M. Well-Known Member

    Messages:
    2,417
    Joined:
    Jul 12, 2004
    The reasons I also asked about the lighter bullets is for the standard 270 Win.

    Anyone having info on those, it would be very helpful...thanks.
     
  12. Derek M.

    Derek M. Well-Known Member

    Messages:
    2,417
    Joined:
    Jul 12, 2004
    Anyone on the smaller bullets? BCs?