In the past, I have noted that, even using the official homicide rates uncritically, the US is not the outlier it is claimed to be in terms of homicide rates. Numerous countries with a Human Development Index values (according to the UN) comparable to several OECD members have homicide rates that are similar too, or much higher than, the US. Moreover, many individual states in the US have homicide rates that are very low and gun-ownership rates that are very high.

However, there is always a fundamental problem with comparing different countries that may employ different methods of collecting data on homicides and processing the data. For example, as noted by the Crime Prevention Resource Center (CPRC), homicide numbers in England and Wales "exclude any cases which do not result in conviction, or where the person is not prosecuted on grounds of self defence or otherwise."

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England and Wales: Homicide Rates Show No Connection at All to Gun Control
The United Kingdom is often held up as evidence of the effectiveness of gun control. After all, since 1920, the UK has experienced increasingly restrictive gun control, leading up to an almost-total ban on handguns, and even many shotguns.

And yet, the homicide rate increased for years after gun confiscation was put into effect: