My guess about what pushes those numbers up in Germany:
- EVERY police officer is armed, no exceptions, no matter what he is doing. Then throw in all the additional guns that the police got (like the mandatory MP5 in every patrol car)
- People that are hunters/have a hunting pass regularly have multiple guns. A hunter will have at least one rifle and a sidearm, usually more. Hunting is popular and has a long tradition in the countryside (where most Germans live)
- Collectors and sport shooters push the numbers up as well. Extremely strict regulations and tough psychological checks prevent misuse in the case of hunters/collectors/sport shooters
- some limited professions (security working in money transportation, bodyguards) have access to revolvers/handguns
- It's rather easy to get very small calibers for shooting sports such as 7mm guns. At least easy to get "by German standards"
- What is considered a gun in the statistics? If stuff like flare/gas guns count as weapons then that'll push up the number considerably, they are pretty easy to get in Germany
As said before, very strict gun laws prevent misuse and prevent them from getting in the hands of the mentally unstable. Getting them from the black market is REALLY hard as well (it's far easier in e.g. the UK). The worst sort of gun that gets used with any sort of regularity in the very few shooting incidents that happen are sport shooting caliber guns with ~7mm, with limit magazine size and low firepower.