Depends where in Europe, in a lot of countries it’s quite common (although not anywhere near the amount of the US), it’s just that the culture is so different that most Europeans don’t flaunt them or see them as a part of their identity like Americans do

Edit: I originally just automatically (ha) assumed you meant all autoloading weapons, but upon further thinking I now realize that you probably meant fully automatic guns. In which case I don’t think those are really a thing outside of like Czechia/Slovakia, but I’m not actually so sure