ΔE 10.9, fair: the same colour family, but not a straight swap. Gunmetal is a little darker, more saturated than Death Metal.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Gunmetal is a little darker, more saturated than Death Metal.
The same difference applies the other way round: Death Metal is a little lighter, 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 Death Metal on the colour wheel See Gunmetal on the colour wheel
All matches: Death Metal equivalents · Gunmetal equivalents