Perhaps they're just blustering, but it increasingly seems that they're serious.
Of course they are serious. These guys would like nothing more than banning guns totally however, they understand that they can't get a total ban passed right now. Right now, they are attempting to lay the ground work for a total ban.
The first step is a registration process. Check out http://www.feinstein.senate.gov/publ...ssault-weapons
for a summary of what they are after. In short; fingerprints and photos for gun owners, approval of local law enforcement allowing you to keep your guns, serial number registration, the banning of certain type of semi auto rifles, handguns and shotguns that accept detachable magazines (read that as all semi autos at some point) but rest assured, you will be allowed to keep your grandfathered guns. Of course on your death, those guns, which you can't sell, or gift, must be forfeited to the Government. Oh yeah, "legitimate" hunting won't be effected. Of course now that they qualifying hunting, you can start to kiss that goodbye too.
This is on the Federal level. Lots of local governments are talking about banning all semi autos to and none seem to care at all about the Supreme Court's decision that it is unconstitutional to do so.
So yes, I'd suggest they are pretty damn serious.