how do I get a bright orange? I am making a cake for a clay shoot and want to get the same bright orange the clays.

Do you need orange buttercream or fondant?

Are you wanting blaze orange like hunters use? It's hard to reproduce. I would look for Americolor electric yellow and electric orange gel paste and kind of playing around with touches of red to get the right shade.

I will be using buttercream for a FBCT, sorry I forgot to specify that.
the clays are bright orange, but not quite as bright as blaze orange.

I'd still go with electric orange alone or electric yellow and start adding red in very small amounts (like end-of-toothpick small). You can always tone it down with a touch of brown.