[O6nop]

I had an interesting conversation with one of those horseback competitors, the only thing that comes out of those rounds is the still-burning powder which is what makes the balloons pop. And it is apparently unlawful to handload those rounds, they have to be purchased from a SASS approved dealer. The reason is the bystanders are commonly lined up along the path of the course and it would be dangerous for any projectile to be loaded, wax, shot or otherwise. The powder presumably burns up within a couple feet of the muzzle. The balloons appear to be just within that range when shot at.

Another interesting side note, they have special hearing protection for the horses.