Ironclad Grey vs Dark Green BS381C/641

How close are they?

ΔE 6.6, close: similar, with a visible difference side by side. Dark Green BS381C/641 is a little lighter than Ironclad Grey.

Can I use Dark Green BS381C/641 instead of Ironclad Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Dark Green BS381C/641 is a little lighter than Ironclad Grey.

Can I use Ironclad Grey instead of Dark Green BS381C/641?

The same difference applies the other way round: Ironclad Grey is a little darker.

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.