If the Hornady A-Max 50 Caliber has a Ballistic Coefficient of 1.050, does that mean it will accelerate? A LOT unbelievable considering the 225 grain .308 lists .670, the .338 285 grain at .720, and the .416 450 grain at .720.
Hornady Ballistic Coefficient
- Thread starter horseman2
- Start date
All of these coefficients makes sense but might be 5% overevaluated.
Take a look at Berger ballistic coefficients (which are very accurate) and you'll see that good secant ogive bullets have these kind of coefficients (Hornady bullet are extremely efficient but very seating depth sensitive).
Alex
Take a look at Berger ballistic coefficients (which are very accurate) and you'll see that good secant ogive bullets have these kind of coefficients (Hornady bullet are extremely efficient but very seating depth sensitive).
Alex
That's really funny!
A BC of 1.0 is just a reference point for drag on a projectile, not the point where it becomes free of all friction. The BC just keeps going up with weight and length of the projectile. For example, a 100lb prjectile lauched from a battle ship would have a BC of 4000. Yeah I just made that up.
BC is made up of a form factor and the sectional density. The form factor describes how efficient the bullet shape is compared to the reference projectile. In the case of the Hornady .50BMG bullet being discussed, the reference projectile used by Hornady is the G1 model. It is a flat based, spitzer shaped projectile with a diameter of 1", a weight of 1lb (7000 grains) and a length of 3".
The .50BMG bullet will have a great form factor, because it is a much more streamlined shape than the G1 projectile, but the G1 bullet has a sectional density of 1, while the .50BMG has a sectional density of 0.429. Combined all together, the high form factor just offsets the lower SD enough to get the BC to over 1.
http://en.wikipedia.org/wiki/Ballistic_coefficient
Mark
The .50BMG bullet will have a great form factor, because it is a much more streamlined shape than the G1 projectile, but the G1 bullet has a sectional density of 1, while the .50BMG has a sectional density of 0.429. Combined all together, the high form factor just offsets the lower SD enough to get the BC to over 1.
http://en.wikipedia.org/wiki/Ballistic_coefficient
Mark
Thank you Mark. That formula will clear it up for many.
Previously when using a bullet with a known BC but no drop figures, I just looked for a similar BC and used my velocities. The 250 grain .338 Nosler Part. and a 6.5 supplied a match. I just did not think a BC could go beyond 1.0 thinking it was a figure whereby velocity was being shed.
Previously when using a bullet with a known BC but no drop figures, I just looked for a similar BC and used my velocities. The 250 grain .338 Nosler Part. and a 6.5 supplied a match. I just did not think a BC could go beyond 1.0 thinking it was a figure whereby velocity was being shed.
Jordan Smith
CGN Ultra frequent flyer
- Location
- Calgary, AB
Mark's got it exactly right. The reason that the G1 BC can go beyond 1.0, is that 1.0 does not refer to perfect aerodynamic behaviour, but is simply a comparison to the form factor of a standardized projectile (the G1 projectile).
