Depends where you live, it's technically considered a pistol because it has no stock...
Where I live, if you've got a concealed permit, you can keep that shit loaded with one in the chamber in your car.
If you don't have a permit, you gotta keep it in your trunk unloaded, or your glovebox in a bag if you can fit it ...
Either way, doesn't take long to pop a trunk, put a 75 round mag in, and chamber a round.