In the aftermath of the tragedy in Newtown, Connecticut, there has been a lot of discussion about the relative prevalence of gun ownership in the United States as opposed to other countries (see here, here, and here for example).
Of course, measuring gun ownership cross-nationally is complicated. One source of data is the Small Arms Survey run by the Graduate School of International Studies in Geneva, Switzerland. Here is their argument for using survey data to measure the prevalence of civilian ownership of small arms:
Ownership laws and practices vary dramatically from country to country and region to region. The most reliable information about civilian ownership comes from official registration reports. But these are incomplete everywhere, missing unregistered weapons. Many countries, moreover, do not require registration, so they have no way of directly measuring civilian ownership. The most comprehensive information on public gun inventories comes from polling and surveys. Unlike official registration data, which only covers legally owned firearms, polling can potentially reveal the approximate total of all guns in civilian hands. Because it relies on voluntary responses to very sensitive questions, however, even polling lacks great reliability. Detailed polls on gun ownership have been conducted in only a few countries, including Canada, Lebanon, and the United States. The largest poll covers some 30 to 50 countries every few years and is undertaken periodically as part of the International Crime Victimization Survey.
Of those weapons in civilian hands, here is breakdown by country as of what looks to be 2007:
Another potentially useful source of information looks to be Gunpolicy.org run by the University of Sydney. This organization does not seem to produce information so much as aggregate publicly available information. That being said, it does seem to be a very quick way to find out details about gun policy and data regarding gun ownership by country; see this page in particular.
John has been referencing academic literature about the politics of gun-control in the United States (here and here). I have been unable to really find anything similar in the comparative literature; most articles seem to be using gun policy as an independent variable to predict rates of violence. The one exception is a twenty-year old article in Government and Policy comparing the politics of gun control in the United States and Canada. If anyone knows of any more relevant (or recent) literature on the comparative politics of gun-control – or even simply interesting studies of other countries – please feel free to leave in the comments.
[Cross-posted at The Monkey Cage]