Truth is, the US doesn't appear to have appreciably more violent criminal acts, fewer in fact, than Britain, just more violent incidents where someone is shot:
Types of Violent Crime
The US has a very specific brand of violence. Perhaps our criminals are just more motivated than the rest of the world, or perhaps having a firearm for every man, woman or child in America ups the ante in confrontations. Either way, the involvement of guns in violent crime (and the defense against violent crime) is a decidedly American phenomena amongst developed nations.
With gun restrictions making it harder to obtain private weapons in the UK, violent crimes involving guns have greatly decreased. The number of total violent crimes, however, is almost double that of the US. Of those crimes, only 19% even involve a weapon, and only 5% of those involve a firearm. That means that of you’re roughly 1/100 chance of being involved in a violent crime in Britain and Wales in any given year, you have roughly a 1/10,000 chance of being in a violent crime involving a gun.
In the US your chances of being involved in a violent crime are less than 1/250.
Alternately, in the US your chances of being involved in a violent crime are less than 1/250. Of those involved with violent crimes, however, you have greater than a 1/10,000 chance of being involved in a violent crime involving a gun. In a country with less than half the violent crime, you have a greater chance of being the victim of a violent crime involving a gun.
Here’s where gun control advocates would say that the proliferation of easily available and private firearms enable gun crimes. This is also where gun rights advocates would point to the much lower violent crime rate in a similarly governed and wealthy nation. In a way, they’re both right. Much as the US is both in line with other developed nations on violent crime, and an outlier–with several cities more dangerous than anywhere in Europe or Asia–violent crime in America is as sprawling as the opportunities to commit crime.
The British seem a rather violent lot. Good thing they don't have an overabundance of firearms like we do.