painting us armor?

What period?  WW2 era is lusterless olive drab.  Straight from the bottle, I find Tamiya to be best.  I lighten it with dark yellow.  Later, US equipment olive drab became darker.

To add on to what T26 said, in the 70's when the US switched to MERDC camo, new vehicles were produced n overall dark green FS# 34079. Later with the switch to NATO camo it was the CARC green.

one could write a book called "50 shades of green" when talking about US armor colors. LOL

This is where I'm thankful that I'm color blind in these tones.  I see them as shades of brown!  (according to my wife)  Oh, and those interesting color blind tests where you're supposed to see something in the "dot matrix field", I'm proud to say I never saw anything!

Definitely hard to keep them all straight!!