ΔE 12.8, fair: the same colour family, but not a straight swap. Medium Seagray BS381C/637 is a little darker, more saturated than Dawnstone.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Medium Seagray BS381C/637 is a little darker, more saturated than Dawnstone.
The same difference applies the other way round: Dawnstone 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 Dawnstone on the colour wheel See Medium Seagray BS381C/637 on the colour wheel
All matches: Dawnstone equivalents · Medium Seagray BS381C/637 equivalents