You might wonder how real ammo gets into a Civil War reenactment. The funny part is that there are so many ways it could happen. Allow me to list the first several theories that pop into my head.
My favorite theory is that some goober spent the entire weekend hunting for turkeys with his Civil War reenactment blanks and didn't realize it. Later, when he discovered what he had done, he didn't want to face the embarrassment of telling his fellow bearded dorks that he used up all of his blanks. So he figured he'd do the reenactment with live rounds and just shoot over the heads of the other actors. No one would be the wiser. It was a good plan until he stepped in a woodchuck hole and accidentally shot some guy in the shoulder.
The wound wasn't fatal, but the Civil War reenactment medics sawed off the victim's legs anyway, just to err on the cautious side.