Burnt Iron vs Gun Metal

How close are they?

ΔE 19.4, loose: different enough that you should pick on purpose. Gun Metal is noticeably lighter, more muted than Burnt Iron.

Can I use Gun Metal instead of Burnt Iron?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Gun Metal is noticeably lighter, more muted than Burnt Iron.

Can I use Burnt Iron instead of Gun Metal?

The same difference applies the other way round: Burnt Iron is noticeably 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.