the whiskey rebellion broke out and some of the agents who collected it were tarred and feathered. by the 1920s it had become the bureau of prohibition in an era when mobsters were glorified in agent elliott ness b one of the untouchables who took down al capone. atf historian barbara showed us elliott ness' actual credentials. >> this is an iconic weapon. >> this is the gun that made the '20s roar. thompson machine gun also known as tommy gun and also nope at is chicago type wire. >> i'm going write my name all >> get out of my way! >> this was pretty he's toe buy? >> al capone bought his in a hardware store. >> hardware store? >> hardware store. >> the tommy gun's deadly popularity led to the national firearms act of 1934. giving the agency jurors addition over a range of gangland weapons. you're controlling american's surprise? >> today the atf remains as unpopular as ever. insists that targets only illegal firearms, but some gun rights advocates believe the agency is a threat to legal gun ownership. in the '90s, the national rifle association referred to atf agents as jack-boot