I looked at the numbers for France, and the 31 firearms per 100 people is generally accepted. But it seems that most of those are firearms that are held outside of legal channels.
Do these numbers seem plausible to you?
Total private guns in France, 19,000,000.
Number of Registered Firearms
The number of registered guns in France is reported to be 2,802,0571
Rate of Registered Firearms per 100 Population
The rate of registered guns per 100 people in France is 4.443
http://www.gunpolicy.org/firearms/region/france
“Registered” is the key word. Even during WWII when France was stripped of firearms by the Nazis, there were families I know who kept firearms in their barns, attics, churches, and elsewhere...,(like in the top of a certain tree.) The French are very good at dissimulation. I would guarantee there are more firearms in France than the “registered” number. I myself owned one that should have been registered and know of others. Particularly prized are WWII weapons which are still highly serviceable. In fact, just a couple of weeks ago, I was thinking about buying one at a “Market” day in SouthWest France.
Most of the firearms credited in France I would think are long arms, some of which “should be’ registered but are probably not. My opinion: The number is low.