Is it the dark forest green as seen postwar? And what got painted this color?
Usual consensus is that the during World War Two, USMC got equipment that was painted No. 9 Olive Drab, as the equipment was being built for all users, the US Army, Land-Lease Allies and the US Marines, and it wasn’t allocated to particular recipients until after delivery. Postwar, the Marines could repaint with Forest Green, as needed. Presumably, most or all of their gear was repainted by the time they went to Korea in 1950.