face, expression
顔 centers on the front of the head: the face itself, and by extension the expressions it shows.
顔 combines 彦 (which likely contributes the sound) with 頁 (head), pointing to the face or facial expression.
The left side 彦 suggests a person standing, and the right side 頁 is a head. Together they form the face, where expressions appear.
For ガン, picture a face with a stern expression like a gunfighter: gun -> ガン, and the face shows the expression.
face; visage; looks; (facial) features
smiling face; smile
face (of person)
face with no make-up; unpainted face
complexion; one's colour; one's color
portrait; likeness; sketch (of a face)
serious look (on one's face); straight face
looks; features
child's face
(outward) looks; features; face; countenance; expression
acquaintance
profile; face in profile; face seen from the side
Japanese morning glory (Ipomoea nil); picotee morning glory; ivy morning glory
(preliminary) meeting; face-to-face introduction
being put to shame; being outshone; being eclipsed; feeling embarrassed
personnel; members; lineup (of a team); roster; cast (of a play)
sleeping face
feigned ignorance; pretending not to know; pretending not to recognize (someone); ignoring
crying face; face of a person who is crying
newcomer; new face
acquaintance; friend; familiar face
portrait; likeness
straight face; composed expression; nonchalant look
to turn up; to make an appearance; to put in an appearance; to drop by
to make someone lose face; to embarrass someone; to make someone look foolish