Ahh, a good, old-fashioned, ideologically driven US political shit-storm is brewing. From the US of A to the rest of the world, sit back and enjoy the show. This has all the makings to be quite interesting.
All the credit in the world to him for admitting that banning assault weapons makes sense though. Even that is often a huge deal for the extremely pro-gun crowd to concede.
The fact is, the whole "We need guns to defend ourselves from the government" argument no longer has any basis in reality, in the age of predator drones, armored personnel carriers and other modern technologies. No group of civilians, armed with shotguns and pistols, and even civilian legal assault rifles (which are often just knock-offs of the real things made from inferior components) has any chance of "defending themselves" against a modern, professionally trained and armed military force.
While the argument to ban guns completely does have some valid points, and some good numbers from countries that have, guns are just too pervasive, both in actual numbers and in cultural significance in the US to ban completely. However, I DO believe that regulations on the types of guns and their ammunition capacities are needed. The 2nd Amendment itself calls for a "well regulated" militia (something a lot of people seem to overlook). You don't need a 30-round magazine on your rifle, you don't need a pistol that can hold 20+ rounds. Hell, I could go out today, and legally buy and own a shotgun that holds 16 shells. As cool as that is, no civilian should have that kind of sustained firepower.
Honestly, I'd be in favor of banning semi-auto handguns along with assault-rifles (although the sheer number of semi-autos basically makes that impossible). It's a whole lot harder to shoot up a room with a 6-shooter than it is with a glocke.
So yes, I support gun ownership (partly because I do believe people should have some form of self defense, and partly because it would be impossible to completely ban them at this point), but we need to have some serious, reasonable limits. The Constitution was designed to be a living document, so that it could change with the times as the nation changed with the times. The only valid reasons for owning a gun in this modern world are self-defense, recreation shooting or hunting, and the laws should be altered to reflect that.
