Wildcat bullets

[hogslayer]

I was talking to Richard a while back and he made mention that his 80, 85 90 grn bullets all were the same jackets ,same length , just have more lead in the core. My question is does this change bc and required twist in these different weights.

[jwp475]

If the lenght of the bullets and the ogive and the boatail are the same on the 3 bullets then the BC is the same and the twist rate required to stabilize the bullet will be the same....

[Cheyenne19]

I thought that the bc would change with weight in the same jacket.

[Eaglet]

Originally Posted by Cheyenne19

I thought that the bc would change with weight in the same jacket.

I believe you're right!

ballistic coefficient: BC=SD/i
where: BC is the ballistic coefficient, SD is the sectional density of the bullet, and i is the form factor of the bullet.

I found this at Dan Lilja's website.

If "i" changes not, it retains its form or shape , then the higher the weight the higher the "SD" would be and the higher the BC.

JWP475 is right on the money about the twist rate needed would be the same but not the BC.

[jwp475]

Normaly you are correct,but the original post stated that the 3 bullets were the same lenght,therefore if the shape is the same then the BC will be identical and only the SD will change........... Normaly a heavier bullet is longer therfore both the SD and BC will increase....BC is a numerical value of a bullets areodinamoc shape and is some what tied to wieght,but not totaly....Other wise all bullets of the same wieght would have the same bc if the shape were the same and this is not the case.... A mono metal bullet(copper) of the same wieght and same shape will have a higher BC than a lead core bullet because it will be longer... A tungstan core bullet of the same wieght as a Lead core bullet and a monometal (copper) will have the lower BC because it will be shorter... 3 different wieght lead core bullets with the same lenght and shape will have the same BC............

[Jon A]

No, the BC's will change. Identical shape, identical amount of aerodynamic drag but still a different BC.

BC is not drag. BC is the effect of that drag on the bullet. The same amount of drag slows the light bullet down faster, meaning the light bullet will have a lower BC even with the same drag on it.

[jwp475]

Explain how the 265 grain 338 Aluminum tipped Wildcat bullets have a higher BC than the 300 SMK..Shawn Carlock shot some and had to plug in a .9 BC to match his drops...

Below is a 265 grain Aluminum Tipped Wildcat compaired to a 300 grain SMK and a solid copper 300 grain bullet