Report as inappropriate

It is generally accepted that you should print with extrusion widths greater than your nozzle diameter. The "go-to" default extrusion width of most slicers is 120% of the nozzle diameter. With a 0.4mm nozzle (what I use as well out of my E3D hot end) that would be 0.48mm.
The reason I choose 0.5mm is because it is much easier to design parts with features that are a multiple of that than pretty much anything else.