Abstract: A pyrotechnic flare signalling device firing mechanism has a tubular casing with a master plunger projecting from one end and slidable in the casing in tandem with a slave plunger which is urged against a stop pin in the casing by a coil spring acting between the plungers. A probe on the slave plunger extends towards a firing pin at the other end of the casing. A ball is located in a dished recess between the firing pin and the probe. The diameter of the ball is such that thrust imparted to the slave plunger by extension of the coil spring is transmitted to the firing pin through the ball when the device is upright whereas the probe is always spaced from the firing pin when the bail is displaced to one side because the device is not upright.