The invention discloses two related improvements over existing trigger mechanisms utilized in pneumatic launching devices\u2014such as pellet or paintball guns. In order to provide a cost-effective and easily assembled fluid reservoir, the filling filter, which reliably prevents the ingress of dirt, extends into the fluid chamber and includes a wall molded onto the housing of the fluid reservoir that adjoins the reservoir filler neck. The enclosure may include a receiver device to process received satellite signals.