A day of mounted shooting!

What do they use for ammunition? There certainly aren't regular bullets in those handguns.

They do use regular handguns, I think they use 45's. The shot is more or less a blank. Its a black powder load that doesn't go very far. That's why they have to get fairly close to break the balloon.

Wow I've never seen that before! That's cool!
Are the horses very bothered about the sound?

They have to train the horses to get used to the bang. We have used fire crackers to get ours used to gunfire. Its a lot cheaper than firearm rounds.
Some of the riders will use a horse ear plug that will muffle the sound for the horse.
I've never done it, just been around it a lot

I knew it had to be something with little trajectory. Black powder though? That would be custom loads and very hard on the guns. I was thinking a standard blank, but then how would it burst the balloon?

You are welcome to visit my place and enjoy that for free! People who own little empty piece of property next to us rent it out to some crazy so they can stay there overnight and shoot. In fact it's forbidden (because they are too close), but they do it anyway (although I haven't seen them for while). I don't really care all that much because I think it's a good training for horses and dogs.

I was actually surprised at how few people used ear plugs.

Honestly I don't know enough to be certain, but I think its a pretty small amount in a custom load. I do know there is no projectile except the powder.
I'll have to ask my friends for specifics. They don't do any re-loading so it has to be something that can be bought.

Here's info about the blanks: J&B Blanks

Thanks, Dashy. I wonder if I can sneak blanks into my ammo box and trick my sons... ;)