Here's the murder rate compare

Number of Murders, United States, 2010: 12,996

Number of Murders by Firearms, US, 2010: 8,775

Number of Murders, Britain, 2011*: 638
(Since Britain’s population is 1/5 that of US, this is equivalent to 3,095 US murders)

Number of Murders by firearms, Britain, 2011*: 58
(equivalent to 290 US murders)

Number of Murders by cros*****ow in Britain, 2011*: 2 (equivalent to 10 US murders).

http://www.juancole.com/2012/07/58-murders-a-year-by-firearms-in-britain-8775-in-us.html

Summary:
UK murder rate is 23.8% of US.
UK firearm murder rate is 3.3% of US.