ΔE 13.0, fair: the same colour family, but not a straight swap. Moon Mist Grey is noticeably lighter than Longbeard Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Moon Mist Grey is noticeably lighter than Longbeard Grey.
The same difference applies the other way round: Longbeard Grey is noticeably darker.
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 Longbeard Grey on the colour wheel See Moon Mist Grey on the colour wheel
All matches: Longbeard Grey equivalents · Moon Mist Grey equivalents