Each printer, slicer and filament combination is slightly different.

And yes the wall settings will make a difference. Also bear in mind that you have a 0.4mm nozzle.
so ideally wall thicknesses should be in 0.4mm steps. ie: 0.4, 0.8, 1.2
I use a 0.5mm nozzle - which I can recommend.
I've printed some really tricky prints with it and it's also great for the quicker 'rougher' prints.

Now that said - that would be in an ideal world :-)
However the actual extruded width of filament is usually larger than the actual diameter of the nozzle.
So the best thing to do is to extruded a short length - let it cool and then measure it with digital calipers. And that's the width you need to set in the slicer.

For example my 0.5mm on the delta tends to come out around 0.52 for pla.
whereas the 0.4mm nozzle on the klic-n-print usually hits 0.44.
Interestingly simplify3d actually wants to set the 0.5 at 0.62 and the 0.4 at 0.52.
So it's always best to measure it yourself, rather than let the slicer guess :-)

I have no idea where that setting is in cura - but this is what it looks like in simplify3d:
(well it will be when I get into the workshop and take a screenshot - don't have s3d on the house computer)

Also might be worth just trying setting the wall thickness to 1mm.

Sometimes the easiest thing is to generate the model slightly smaller and see if that works better :-)
Or keep the outside diameter and make the wall a little thicker at 1.2mm.
It's easier to sand down the inside of a tube than the outside - with the right file.

3d printing is as much an art as a science, quite often you need to tinker and play around before you hit on the perfect combination for a particular job.
And also don't forget files and sanding blocks for that 'fine tuning' :-)
https://www.amazon.com/Superfine-Dif...0319666&sr=8-5
They are generally a LOT cheaper from your local discount or buck/pound store :-)
I think I pay £3 for 12. each block has several different grit surfaces.

The other thing I use a lot are these: https://www.amazon.com/Hardened-Stre...0319758&sr=8-3
Great for finetuning fiddly prints.