It is a fairly consistent number as reported by several websites over the past several years. my post showing a comparison of France as compared to Great Britain uses Wiki, but others are available. Simply google Firearms per country or any variable.
Knowing the French as I do, I think the number is low for France in all reality. I believe France is more heavily armed than is thought. I hold a Lifetime French Hunting License (since 1988) and have always placed well in competitive Trap Shooting there so I’m quite familiar with the subject.
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
My DIL and SIL(who is French) live in rural France. He has a shotgun and license because he and his Dad and brother hunt. He has to renew the license periodically.