there is provided a powder actuated tool effective to drive a metallic fastener into a workpiece , for example , a nail gun . the pressure to drive the fastener is generated by combustion of an flammable propellant mix that is ignited by a primer flash . the primer flash having been generated by ignition of a combustible gas by discharge of an electric arc in the tool barrel . the combustible gas is lead - free such that the operator and the environment are not exposed to dangerous lead residue during use . the use of a solid propellant generates higher pressure and more effective driving of the metallic fastener than is achieved with powder actuated tools driven solely by combustible gases .