Field Gray vs Russian AF Grey N.3

How close are they?

ΔE 10.0, close: similar, with a visible difference side by side. Russian AF Grey N.3 is a little lighter, more muted than Field Gray.

Can I use Russian AF Grey N.3 instead of Field Gray?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Russian AF Grey N.3 is a little lighter, more muted than Field Gray.

Can I use Field Gray instead of Russian AF Grey N.3?

The same difference applies the other way round: Field Gray is a little darker, more saturated.

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.