America is lucky in that its home grown terrorists have ben to be blunt a bit crap.
If you tried to smuggle this:
http://ichef.bbci.co.uk/news/624/cpsprodpb/0B22/production/_...
and this:
http://ichef-1.bbci.co.uk/news/624/cpsprodpb/11A62/productio...
into the USA, you'd be facing about 630 years in jail, not 30.
You might not like it, but we do. Our system of gun control is overwhelmingly popular.
http://data.worldbank.org/indicator/VC.IHR.PSRC.P5 http://www.inquest.org.uk/statistics/fatal-police-shootings
The only way they could be imported is by a licensed dealer, for sale to the military or law enforcement.
It's likely you just meant to make a more generalized comparison of the laws, but most people wanting to import the weapons in that article into the US would need to smuggle them.