ΔE 36.8, loose: different enough that you should pick on purpose. Gunmetal is a little darker, much more muted than Dwarf Shield.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 37). Gunmetal is a little darker, much more muted than Dwarf Shield.
The same difference applies the other way round: Dwarf Shield is a little lighter, much 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.
See Dwarf Shield on the colour wheel See Gunmetal on the colour wheel
All matches: Dwarf Shield equivalents · Gunmetal equivalents