Warplock Bronze vs Gun Metal

How close are they?

ΔE 15.7, loose: different enough that you should pick on purpose. Gun Metal is a little lighter, more muted than Warplock Bronze.

Can I use Gun Metal instead of Warplock Bronze?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Gun Metal is a little lighter, more muted than Warplock Bronze.

Can I use Warplock Bronze instead of Gun Metal?

The same difference applies the other way round: Warplock Bronze 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.