Thread: Twist rate vs velocity vs bc

Originally Posted by veitnamcam

So for any given bullet in theory for the same pressure more velocity should be obtained by a slower twist using less energy and friction to rotate the bullet, what are your experiences with this?

An over stabilised bullet may not tip and follow its arc of travel but stay spinning on the axis of the bore at long range increasing drag as it falls threw the air, anyone observed this?

How does the stability factor affect the way the bullet transitions the sound barrier at ELR or is this more a function of the form of the bullet?

In Bryan Litzs latest book he says the difference in velocity from slow to fast twist is typically less than the usual ES so basically no difference.

Also a faster twist on a bullet gives it a slightly higher BC than a slower twist, so that would probably cancel out or over ride any loss of velocity at distance.

It is possible that over stabilised projectiles can nose up causing a loss of BC at extreme range.

A client has tested my .375 425 CEB projectiles in my old 7.25 exit 375 DCM at 4000m

They would have been way subsonic but they were still stable & nose up even with the 20-25 degree angle of decline when they hit the target

Even though they were nose up they still went transonic fine & the trajectory was repeatable.

I'm really looking forward to testing of the 400 & 425s in my 40" 1-9 twist 375 DCM & my 452s in the 7.25 exit twist 375 DCM, should be interesting.

It doesn't really matter what is "supposed" to happen in theory, what matters is what happens in practice, like the 208s in the 14 twist in a previous post