ΔE 10.4, fair: the same colour family, but not a straight swap. Rus. AF Grey Prot. Coat is a little darker, more muted, warmer than Medium Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Rus. AF Grey Prot. Coat is a little darker, more muted, warmer than Medium Blue.
The same difference applies the other way round: Medium Blue is a little lighter, more saturated, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Medium Blue on the colour wheel See Rus. AF Grey Prot. Coat on the colour wheel
All matches: Medium Blue equivalents · Rus. AF Grey Prot. Coat equivalents