ΔE 18.7, loose: different enough that you should pick on purpose. Rus. AF Grey Prot. Coat is noticeably darker, more saturated than Frostbite.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Rus. AF Grey Prot. Coat is noticeably darker, more saturated than Frostbite.
The same difference applies the other way round: Frostbite is noticeably 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 Frostbite on the colour wheel See Rus. AF Grey Prot. Coat on the colour wheel
All matches: Frostbite equivalents · Rus. AF Grey Prot. Coat equivalents