Yes, called spin rate, I think, for bullets. They have tables for twists, bullets and velocities for unmentionable projectiles so folks can figure when conicals will go unstable. Shows up in 1000 match bullets where loss of velocity can't keep the spin going and tumbling occurs. [crossing the sound barrier is another destabilizing issue] Much more important for them than roundball. If roundballs leave the muzzle stabilized, they will have accuracy and spin rate won't mean much in the distances they are usually intended for. If they don't stabilize before launch-bad deal. Not tumbling is their strong point. I think that's at least partly why some MLs w pitted barrels can no longer do a roundball well but still have some accuracy w conicals, provided the twist is sufficient for them. The bearing surface of the roundball is so short that any slight upset [irregular drag on the patch etc.] from the get go sets them off kilter. The conical has more bearing surface for its spin to overcome that. I have a ML like that. More old pitting in some grooves than others and the ball just can't get going w any stability. I have polished the heck out of it and even the patches look decent. Still no good w RBs. It now shoots conicals ok. SWWow! I've never thought about the RPMs a projectile spins at. Has someone actually calculated that?