The earliest guns, along with the earliest artillary,
used balls as projectiles. This is the obvious chouce of projectile shape
for a round opening. Still, the balls did have some problems. A round ball
will shed it's velocity and energy rather quickly, which is why modern shot
gun shells, firing a load of round shot, have such limited range. Balls are
not directionally stable; they go where their inertia takes them. even so,
balls are easy to make, and for centuries, no one really had any better alternative.
Somewhere down the line, an unknown gunsmith discovered
that ridges or groves in a gun barrel made it more accurate. Soon everyone
was doing it, and the new rifled arms began to replace the traditional musket.
Spinning the balls turned them into miniature gyroscopes, with great directional
effect of different rates on stability
the effect of different rates of stability on lethality
gyro rate stays the same even when bullet slows down
laws of gyro stability