That sounds like level 2 of the scavenging perk in the INT tree. Level 1 was finding screws and uncommon materials when scrapping guns, level 2 is finding rare

That sounds like level 2 of the scavenging perk in the INT tree. Level 1 was finding screws and uncommon materials when scrapping guns, level 2 is finding rare materials when scrapping guns as well as highlighting tagged components in the game.