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M.V. x (12 / twist rate in inches) x 60 = Bullet RPM

or: M.V. x 720 divided by the twist rate in inches = Bullet RPM

Example #1: for a bullet travelling @ 2,800fps in a 1:12 twist barrel: 2,800 x 720 divided by 12 = 168,000 RPM!

Example #2: for a bullet travelling @ 3,000fps in a 1:8 twist barrel: 3,000 x 720 divided by 8 = 270,000 RPM!

I was amazed. Bullets have to be made tough. I tried to imagine a hollowpoint spinning that fast as it expands and cuts through a game animal. The thought of that dynamic spin rate hasn't left this tired old brain to this day. Muzzle velocity isn't the only physical characteristic that produces an accurate delivery downrange. The gyroscopic stabilization effect of a high speed spin helps. Velocity and twist rate are co-related and can be matched or specified for the performance one wants. There are also transonic effects and barrel heat and friction to consider. So no wonder you may find some bullet jacket residue in your barrel. There is a lot of "little stuff" that is important to what we do. I'm sure this is not news to many of you.