Hi and welcome Christian,
6mm-ammo are a good brand. The non-bios work well for me and most others but some people have reported issues with them jamming their guns so it can depend on what gun you use.
The problem with bios is they are hygroscopic meaning they absorb water even from the atmosphere. This can make them swell and jam when used. Yes, a gun can be damaged by BB's getting stuck or shattering inside.
So you must keep them in a very dry place. They may still swell after some time and become unusable.