For AKiwi (and any other readers here who don't already know):
In addition to Kenosha Kid's statements and Links... in the US civil war era, the term Minie-bullet (or Minie-ball) refers to any of the hundreds of varieties of rifle bullets which had the basic form originally invented by Mr. Minie. (That form is a cylindro-conical lead bullet with a large cavity centered in the bullet's base.) Please note, the term Minie-bullet is a "generic" description. Having different numbers of grooves or bands (or none) on the bullet's body doesn't matter ...it is still basically Minie's design.
Most of us diggers & collectors were initially mystified by the term "Minie-ball," because the bullet obviously is not a ball. But in all previous years (even centuries) before Minie's invention, almost all bullets were ball-shaped, so the vast majority of civil war soldiers (and writers) insistantly referred to Minie type bullets as a "Minie-ball."
That term has stuck to them even to this day. If you ask a civil war relic-digger what he found last weekend, he will probably say "Oh, just an eagle button and a few Minie-balls." (But if he were writing, he would probably mis-spell it as "mini" balls.) ;-)