ΔE 14.1, fair: the same colour family, but not a straight swap. Skrag Brown is a little darker, more saturated, warmer than Red Primer.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Skrag Brown is a little darker, more saturated, warmer than Red Primer.
The same difference applies the other way round: Red Primer is a little lighter, more muted, cooler.
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 Red Primer on the colour wheel See Skrag Brown on the colour wheel
All matches: Red Primer equivalents · Skrag Brown equivalents