Yes my friend I know about class 3 weapons, I currently own 2 MGs and 3 suppressors. As for the semi version of the the HK 416, HK has purposly designed it to not be compatible with any registered M16 lower RDIAS or Lightning link, where as if you would like to spend the 3k+ some people are selling the actual 416 uppers for you could get one to work with your reigstered MG. As for the 1968 Gun Control Act it just banned MGs from importation, you could still legaly import them and convert them but could not import the real deal. As I said previously the 1986 Firearms Owenrs Protection Act banned the manufacture of NEW machine guns for civilian owner ship. Anything previously made before that as long as it was not a dealer sample can be owned as long as state and local laws are followed.