Actually greg may be slightly confused, that helmet style is reminiscant of all World Eaters ( / Khorne Berzerkers),
Kharn therefore does where a similar helmet, but the biggest give away that this is not him is his left arm, due to the excessive use of his famed chain axe (otherwise known as ‘gore child’) his arm is said to have grown too big to fit his armour, so as represented in all art concerning Kharn and his model.