The Billet button is surprisingly well placed. Your thumb naturally rests on it when you pick it up or if you're a lefty then your finger finds it easily. The 'pinky', however, should be tucked underneath the device for added support. Those who prefer the pinky out method should be shot at dawn!
Then simply turn the device upside down, turn your head upwards and toot (upturned tooters will also be shot at dawn)I'm a right handed finger user.
I tend to finger the river with the middle digit
I'm one of those awkward thumb firers .......... which is why I don't have a BB ........I tend to finger the river with the middle digit, if using the right hand, or the thumb if using the left. Agreed though @Discomatt , it’s ingeniously placed. I’m going to assume @Simon G and @Crewella are basing their opinions on presumption rather than experience.