Dark Reaper vs Dark Seagray BS381C 638

How close are they?

ΔE 11.1, fair: the same colour family, but not a straight swap. Dark Seagray BS381C 638 is a little lighter, more muted than Dark Reaper.

Can I use Dark Seagray BS381C 638 instead of Dark Reaper?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Dark Seagray BS381C 638 is a little lighter, more muted than Dark Reaper.

Can I use Dark Reaper instead of Dark Seagray BS381C 638?

The same difference applies the other way round: Dark Reaper is a little darker, 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.