Rifled barrels for spherical projectiles?
Not sure if this is the correct forum, but I thought my "blackpowder brethren" might be the right people to ask:
Why would you use a rifled barrel to fire spherical bullets? I was looking at the Wikipedia article on rifling, and they had a picture of an old cannon that used round cannonballs with little "winglets" on it that were meant to engage rifling grooves in the cannon bore to make the ball spin in flight.
I can understand the need for rifling with pointed bullets, because imparting a spin on the bullet helps prevent tumbling and keeps the pointy end of the bullet facing forward. But round balls don't have a "front" or a "back", so I'm not sure why it would be necessary to have them spin during flight.
What am I missing?