I don't think as a subject of the UK that you have much room to talk. The US has a higher total crime rate but it's also a much larger nation. The per capita crime rate in the US is about 1 per every 26 persons where as the crime rate in the UK is about 1 per every 9.5 persons. So yes, the US does have a higher murder rate than the UK compared to the rest of the worlds it's still fairly low. Russia has far more stringent gun control laws and far more media censorship than the US does but it's murder rate is more than triple that of the US. When you compare regions North America as a whole has nearly the same muder rate as Europe (4.7/100,000 in NA and 3.5/100,000). Then when you look at other regions, South America and East Europe from example, which have far more stringent gun controls and far more stringent media laws than the US have nearly 5 times and 2 times the murder rate as the US does.
That would indicate to me that media exposure to violence and easy access to guns are not quite the factors in violence that you seem to think they are and that political, cultural and economic factors have a far greater influence on violence.