ΔE 12.9, fair: the same colour family, but not a straight swap. Obsidian Black is a little lighter, much more muted than Bronzegrun.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Obsidian Black is a little lighter, much more muted than Bronzegrun.
The same difference applies the other way round: Bronzegrun is a little 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 Bronzegrun on the colour wheel See Obsidian Black on the colour wheel
All matches: Bronzegrun equivalents · Obsidian Black equivalents