We do have quite a few federal and state laws that make it more difficult to purchase guns and which limit the types of guns you can own, as well as limiting the size of magazines for automatic weapons. And those actually work quite well, as long as we are talking about purchasing weapons legally.
Illegal gun sales are the reason that many of our cities suffer from disproportionately high numbers of shootings, in spite of having the strictest gun control laws. We have had as much success stemming the tide of illegal guns into the country as we have had in stopping drugs from being brought across our borders in massive amounts. A big nation with wide borders and lax border security (due, in part, to peaceful relations with our neighbors for so long) is going to have a difficult time keeping contraband from streaming in.
I do want to point out, again, that many parts of the country are quite safe and have very low crime rates, regardless of the levels of gun ownership. The issues that lead to shootings of any kind have less to do with the availability of guns and more to do with socioeconomic conditions, which are kept in a volatile state because it's politically expedient to do so.