Well ?? Does anyone know ??

And for that matter, what exactly is the definition of "ball" ammo ? For example, if it's not jacketed, is it still "ball".

Sorry, if this is a dumb question, but hey, I didn't know the answer and figured I'd ask.

Thanks

Just an educated guess ...

All early firearms fired a smooth lead ball.
Even when the rifled barrel was invented, they continued to use a lead ball wrapped in wadding to provide some contact with the rifling so that spin would be imparted to the lead ball.

Accuracy was given a big boost when, according to Mail Call, a French military officer named Minie invented the pointed lead bullet with rings at the base of the round which grabbed onto the barrel rifling. US soldiers called it the "minie ball", even though it was not a sphere.

A firearms glossary I came across on the internet said [the term "ball" is most commonly used in military terminology and was originally a spherical projectile but now is generally a fully jacketed bullet of cylindrical profile with round or pointed nose.]

Putting these two items together, and knowing the military's tendency to abbreviate, I would guess the term "minie ball" was eventually  shortened to just "ball".

When the metallic cartridge came into common use, the bullet was initially still just solid lead. When nitrocellulose (smokeless) gunpowder was invented and bullet velocities increased, cupro/nickel jacketing was put over the lead core to increase the solid lead bullet's penetration characteristics. With greater ammo velocities came more tinkering and other types of rounds were invented, such as armor piercing and incendiary, and I would guess they continued to use the term "ball" to describe a cartridge in which the bullet was just a plain, solid anti-personnel projectile.

Sound plausible?

A less common case of the phrase "ball" ammo describes the use of the testicles of your captured enemies as projectiles.  While offering little in the way of terminal [blue]ball[/blue]istics, this approach has profound psychological effects.

No flame here, but I thought it referred to the original type of smokeless powder used in military rifles:  Ball-Grain Powder.  The process resulted literally in little spheres of nitrocellulose.  "The grains are sieved under water and are then dried for use in shotguns.  If the powder is to be used in rifles, it is passed in a slurry between warm steel rollers by which all the grains are reduced to the same least dimension or web thickness" (Tenney L. Davis, Ph.D., The Chemistry of Powder and Explosives, pp. 328-330).  The entire cartridge was then referred to as "ball ammo" because of the type of powder it used and the phrase stuck.

So noted.  You learn something new every day.