US Patent 10145636 Reduction of first shot noise in firearm sound suppressors

First round shot noise and flash caused by combustion of oxygen contained in the air residing in a firearm sound suppresser can be reduced by providing a valve that communicates with the baffled interior space of the suppressor, and connecting a source of non-flammable gas such as CO2 to the valve in order to inject the gas into the suppressor. The non-flammable gas displaces the air in the suppressor, removing the oxygen available for combustion when the first shot is fired.