ΔE 60.2, loose: different enough that you should pick on purpose. Dark Gunmetal is noticeably lighter, much more muted than Gold 79.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 60). Dark Gunmetal is noticeably lighter, much more muted than Gold 79.
The same difference applies the other way round: Gold 79 is noticeably darker, 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 Gold 79 on the colour wheel See Dark Gunmetal on the colour wheel
All matches: Gold 79 equivalents · Dark Gunmetal equivalents