This post is from 2007. There’s a 2012 update with more recent statistics.
In the UK (population c. 60.5m) there were 765 reported incidents of murder for 2005-6 (Home Office, undated) – a rate of about 1.1 per 100,000.
In the US (population c. 298.5m) there were an estimated 16,137 homicides in 2004 (FBI, 2006a) – a rate of about 5.4 per 100,000. Of these, 10,654 were carried out with guns (FBI, 2006b).
Federal Bureau of Investigation (2006a). Bureau of Justice Statistics. Homicide trends in the U.S.. Long-term trends. Available from: http://www.ojp.usdoj.gov/bjs/homicide/tables/totalstab.htm.
Federal Bureau of Investigation (2006). Bureau of Justice Statistics. Homicide trends in the U.S.. Weapons used. Available from http://www.ojp.usdoj.gov/bjs/homicide/tables/weaponstab.htm
Home Office (undated). ‘Homicide’ – long-term national recorded crime trends. Available from: http://www.crimestatistics.org.uk/output/page40.asp.