Well, so far only about 65,000 firearms have been surrendered, out of a total French population of about 65 million, so that's not a huge haul.
Considering the number of firearms that must have been left on the battlefields of France during WWI and WWII, 65,000 unregistered arms just doesn't seem like very many. While I have little doubt the armies of both sides did their best to scrounge up all sorts of weapons and ordnance left in the wake of combat operations, I wonder how much ended up stuffed in haystacks and hidden in barns out in the countryside.
Put another way, had I such an opportunity, I know I would have had weapons of all types, from both sides, and kept my mouth shut about it, especially with the Soviets breathing down Europe's collective neck.
While many have characterized the French as 'surrender monkeys', that does great disservice to the 71% of French troops wounded (4.2 million) or killed (1.4 million) in WWI, and the 217,600 who died in WWII in France as it was overrun, not to mention the over 1 million dead in Indochina (military and civilian). French forces delayed the Nazis enough for Dunkirk to happen. Without that, WWII might have had a different outcome. YMMV