Not sure that it applies here, but in some countries in Europe, for non-citizens they require proof that you can own a gun in your home country (there was a problem with residents buying guns to smuggle back home during the Balkan wars). I'm originally from a country where pretty much only criminals can have guns, so that was a non-starter for me, and I don't know how you would go about proving that as an American (where federally people can own guns without any permit).

In any case, I'll bet your life will be easier if, before leaving for Germany, you get a CPL from your home state, an FBI background check (these are the fingerprint-based ones that take months, so get started now), state background check if your state issues those. That should cover your bases for the home country requirements (proof that you can own at home and proof of clean criminal history). In fact, you may want to get your background checks even if you won't buy a gun - in Switzerland for example they may ask for that when you go register locally as a resident.