Abstract: A sprayer device mounts to the barrel of a firearm and includes a housing having forward and rear portions which hold opposite ends of a spray canister containing a pressurized charge of a debilitating chemical substance. The forward and rear portions are adjustably positionable along an elongate brace for accommodating a variety of spray canister sizes. When held between the forward and rear portions of the housing, a nozzle stem of the spray canister is positioned for engagement with a front cap of the housing in axial alignment with a discharge aperture. A trigger actuator on the rear portion is operable to urge the spray canister forward relative to the housing so that the nozzle stem is depressed against the front cap, thereby causing release of the debilitating chemical substance through the discharge aperture in a forward trajectory.