ΔE 9.4, close: similar, with a visible difference side by side. Gunmetal Blue is more saturated than Heavy Armour.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Gunmetal Blue is more saturated than Heavy Armour.
The same difference applies the other way round: Heavy Armour is more muted.
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 Heavy Armour on the colour wheel See Gunmetal Blue on the colour wheel
All matches: Heavy Armour equivalents · Gunmetal Blue equivalents