ΔE 24.7, loose: different enough that you should pick on purpose. Warm Grey is noticeably lighter, cooler than Hunter's Quiver.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Warm Grey is noticeably lighter, cooler than Hunter's Quiver.
The same difference applies the other way round: Hunter's Quiver is noticeably darker, warmer.
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 Hunter's Quiver on the colour wheel See Warm Grey on the colour wheel
All matches: Hunter's Quiver equivalents · Warm Grey equivalents