The ATF moved to re-classify wetted nitrocellulose to "high explosive" recently. They got a ton of pushback and had to back pedal the decision and put it on temporary hold. The snarky coverage by the left-wing SNOPES writer aside...it was clearly yet another attempt to quietly "nibble at the edges" of the Second Amendment by executive fiat. And it's not settled yet.
http://www.snopes.com/atf-reclassifies-wetted-nitrocellulose/
http://www.snopes.com/atf-reclassifies-wetted-nitrocellulose/