I just took apart and tried to transplant the washers from my G10 Native into the Salt Native.
I measured their dimensions: outer diameter 10.93 mm and inner diameter 4.95 mm.
But.
The distance between the bushing pivot 'shoulders' in the Salt Native is 3,75 mm while the same is 3.25 mm in the G10 Native. So because the inner diameter of the washer in the G10 is sized to go in between the scales and the pivot shoulder, and because the blade thickness is 3.2 mm, it never makes contact with the blade.
So the correct washer size for the Native 5 LW models should be at least 0.25 mm thick with a 6.5 mm inner diameter and 10.9 mm outer diameter.
I will look for PB washers and will do a mod.
Pictures:
The washer from the G10 Native fits perfectly in the FRN mold:
But the bushing pivot is oversized to introduce an airgap between the scales and the blade.
In practice though, in time, material fatigue leads to deformation and the blade and the scales will start touching, resulting in rough action.