*headscratch*

you just made me realize it's already been what, two months, since I've run a CM?

If I recall correctly, it's click on the Cannon (X) (This causes your hotbar to change, and you have one action)
Perform the action (R2 + Circle I think, but if you can't do this, stop playing lol coz it is the regular hotbar)
This is where the circle comes up, cursor over the boss.
I'm fairly certain it's (X) To confirm, you fire and then go reload the cannon . . .