Uhh...chavs with guns. What a nightmare that would be. They're bad enough with fireworks and air rifles! Having the ability to shoot a chav wouldn't make them any more polite, it would just result in a lot of dead chavs, a lot of vendettas, and a lot of decent people going to jail for murdering chavs who just pushed it too far.
Chris, if they play loud music at 10pm again, don't hesitate - call the police. You're within your rights under the Antisocial Behaviour act and Breach of the Peace laws. If the police don't do anything, phone them again. And again.