the AR-15/m16 does need to be cleaned every so often.
it hardly needs to be cleaned as much as that old gunny said --
we kept ours sanitary clean--- one thing i'll admit is a lot of the cleaning was just "busy work" in case the brass was looking--LOL
the chamber and the bolt carrier needs to kept reasonably clean. it will run pretty dirty if it has too .
the ar-15/m16 ain't no AK in that it won't EAT dirt and dust and like it--