Even with the hurdles that silencer buyers must deal with demand for the items is already increasing fueled by a new generation of suppressors and some slick marketing There are now more that 1 3 million of them registered with the Bureau of Alcohol Tobacco Firearms and Explosives up from about 360 000 just five years ago There s also evidence to suggest that as silencers have gained a foothold with gun owners some are winding up in the black market 