Weapon Bronze vs Old Copper

How close are they?

ΔE 22.8, loose: different enough that you should pick on purpose. Old Copper is noticeably darker, much more muted than Weapon Bronze.

Can I use Old Copper instead of Weapon Bronze?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Old Copper is noticeably darker, much more muted than Weapon Bronze.

Can I use Weapon Bronze instead of Old Copper?

The same difference applies the other way round: Weapon Bronze is noticeably lighter, much 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.