Demoncase, as strange as it sounds we can ( in this state) go buy an AR 15 after passing a background check but we can't go out and buy an air rifle suppressor. One would need special permit/tax stamp, permission from local sheriff, all the same things needed for a full auto weapon. Meaning most will never see one.
There was a case of a guy coming over from the UK some years back and bringing then gifting an air rifle suppressor to an American. I know the American was prosecuted for possession of the suppressor and I'm unsure about the visitor from the UK. He was interviewed and seemed incredulous that despite being able to purchase "assault rifles" ( not the correct term but used incorrectly so often it has taken on the meaning), an air rifle suppressor was a felony with serious prison time.
*note It has been argued that there are between 9,000 and 20,000 different gun laws , local, state and federal in this country. I'm not sure anyone actually knows http://www.washingtonpost.com/blogs/fac ... _blog.html