I was looking on the JBM ballistics chart and had a question on the area that you enter the ballistics coefficient. There is another spot that asked for a G1,G2,G3,G4,G5,G6,G7,G8,GI,GL,RA4. Can someone tell me what these are for? Im trying to make a chart for the sierra 175 smk's with a B.C. of .496 and a Nosler 165gr with a B.C. of .475.
newbie B.C. question
- Thread starter kingfamous
- Start date
Re: newbie B.C. question
Different form factors and models.
Concern yourself with G1 and G7.
G1 is the standard, but it will be great to see it change to G7. G7BC's are more useful because they are not sensitive to muzzle velocity like G1's are.
If a G1 BC was derived and is useful for 3000 FPS, if your rifle is only shooting 2750 fps, then that G1 BC wont be as accurate for you.
Also the G7 takes into consideration loss of MV over the flight of the bullet.
If Bryan Litz is around to step in im sure he can overwhelm you with a wealth of information concerning BC's and form factors.
Different form factors and models.
Concern yourself with G1 and G7.
G1 is the standard, but it will be great to see it change to G7. G7BC's are more useful because they are not sensitive to muzzle velocity like G1's are.
If a G1 BC was derived and is useful for 3000 FPS, if your rifle is only shooting 2750 fps, then that G1 BC wont be as accurate for you.
Also the G7 takes into consideration loss of MV over the flight of the bullet.
If Bryan Litz is around to step in im sure he can overwhelm you with a wealth of information concerning BC's and form factors.
Re: newbie B.C. question
Borrowed from wikipedia
"
G1 or Ingalls (by far the most popular)
G2 (Aberdeen J projectile)
G5 (short 7.5° boat-tail, 6.19 calibers long tangent ogive)
G6 (flatbase, 6 calibers long secant ogive)
G7 (long 7.5° boat-tail, 10 calibers tangent ogive, preferred by some manufacturers for very-low-drag bullets[10])
G8 (flatbase, 10 calibers long secant ogive)
GL (blunt lead nose)
"
Borrowed from wikipedia
"
G1 or Ingalls (by far the most popular)
G2 (Aberdeen J projectile)
G5 (short 7.5° boat-tail, 6.19 calibers long tangent ogive)
G6 (flatbase, 6 calibers long secant ogive)
G7 (long 7.5° boat-tail, 10 calibers tangent ogive, preferred by some manufacturers for very-low-drag bullets[10])
G8 (flatbase, 10 calibers long secant ogive)
GL (blunt lead nose)
"
Re: newbie B.C. question
http://02b0516.netsolhost.com/blog1/?p=62
If you don't have time to read the whole thing, at least look at the pictures of the G1 and G7 standard projectiles.
http://02b0516.netsolhost.com/blog1/?p=62
If you don't have time to read the whole thing, at least look at the pictures of the G1 and G7 standard projectiles.
