I presume that the easiest way is to start the alternating flashing LEDs when the motor has reached full speed, or after a set time from pushing the button?
The spinning will be to fast to see if the barrels are aligned with the muzzle when the LEDs are flashing, so that kind of precision is not needed, and that way i wouldn´t need any reed switches.
Is that i feasable thought?
And the sound and ammocounter could start at the same time as the LEDs in that case?