Hey all,
I'm trying to use the Twist Rate Calculator to determine the highest BC bullet I can shoot in my 1:12 Howa .223. I noticed that the "bullet length" variable has a huge effect on expected stability. With the actual OAL of 53gr V-Max including the polymer tip (.833"), it says this bullet at 3300fps is UNSTABLE. In an even more surprising example it states the 40gr V-Max OAL (including tip- .686") @3700fps is only marginally stable. If I subtract the tip length (approximately .153") from the bullet length variable, the SG jumps way up and both fall well into the "comfortably" stable sector. Of note, both these bullets have a cute little boat tail. The calculator states "stability formula is most accurate for boat tail bullets, and typically underestimates stability for flat based bullets" and while these bullets are not flat-based, their boat tails are quite minor.
So anyways, when using this stability calculator - does it make sense to not include a polymer tip in the bullet length due the the polymer being much lighter than the rest of the bullet construction? Or is this weird output possibly due to these bullets not having as much of a boat tail as a typical BT bullet?
I'm trying to use the Twist Rate Calculator to determine the highest BC bullet I can shoot in my 1:12 Howa .223. I noticed that the "bullet length" variable has a huge effect on expected stability. With the actual OAL of 53gr V-Max including the polymer tip (.833"), it says this bullet at 3300fps is UNSTABLE. In an even more surprising example it states the 40gr V-Max OAL (including tip- .686") @3700fps is only marginally stable. If I subtract the tip length (approximately .153") from the bullet length variable, the SG jumps way up and both fall well into the "comfortably" stable sector. Of note, both these bullets have a cute little boat tail. The calculator states "stability formula is most accurate for boat tail bullets, and typically underestimates stability for flat based bullets" and while these bullets are not flat-based, their boat tails are quite minor.
So anyways, when using this stability calculator - does it make sense to not include a polymer tip in the bullet length due the the polymer being much lighter than the rest of the bullet construction? Or is this weird output possibly due to these bullets not having as much of a boat tail as a typical BT bullet?
