The predominant myth that's perpetuated about gun laws and gun sales here in the U.S. is that the 'mover' behind opposing any modification to existing laws is the gun manufacturer's themselves. Fact is, at quantum levels, many more guns are bought and sold individually between private parties. This occurs in response to advertisements but primarily at gun shows.
Recently, the concern about the Federal government attempting to impose restrictions on gun ownership has increased the attendance at such shows. One I try to visit each year usually has attendance of around one to two thousand people over a 5 day period. Although I couldn't go this year, it just finished and had attendance of eight thousand.
The fact that's understandably difficult for citizens of other countries to comprehend is that the U.S. has had a firearms culture for centuries, back before we were even a country. The Second Amendment to our Constitution was added, primarily to guarantee the citizens of the U.S. would always have the means to defend themselves against a tyrannical government.
Thomas Jefferson had two salient points in these quotes:
"The constitutions of most of our States assert that all power is inherent in the people; that... it is their right and duty to be at all times armed."
--Thomas Jefferson to John Cartwright, 1824.
"Laws that forbid the carrying of arms . . . disarm only those who are neither inclined nor determined to commit crimes . . . Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man."
--Thomas Jefferson, quoting Cesare Beccaria in On Crimes and Punishment (1764).
In my opinion his views are as valid today as they were in the late 18th century. Of course I'm a westerner (living in the western U.S.) and have used guns of all varities since I was very young... it's just a way of life and neither me nor anyone I know has ever had the inclination to murder anyone, let alone children.
By the way, the young man responsible for the tragedy at Newtown Connecticut, used his mother's lawfully obtained firearms in one of the most gun restrictive States in the Union. Of course, he killed her too. He was severely deranged and had been for years.
I firmly believe the entertainment culture (movies, video games and even TV) today has as much to do with these episodes as anything.
Lastly, in the 1990's President Clinton imposed restrictions on the AR-15. type "assault weapons" and the firearm related deaths increased significantly. The restriction was rescinded by the Supremem Court and the related deaths immediately decreased... by 48%. (The day before the school shootings a man in China attacked a similar school with a large knife or sword and injured 20 similar students... luckily, none were killed, but that was certainly his intent... seen here:
http://www.nydailynews.com/news/national/man-attacks-22-kids-knife-china-school-article-1.1220230 ).