Until recently, portraits of him, commonly depict his helmet as
a solid structure with winged corners, the shapes seems to be drawn
more rigid over the years, as each artist interprets them differently...
However many ottoman sources depict it differently,
with the emphasis on its chain mail pattern, sometimes
raised or relaxed, which may point out that it may be a
raised mail aventail after all, rather than a full helmet...
The same armor set is also depicted on later sultans such as
Mustafa II (1664 - 1703 / left) compared here with Murad IV (right)
notice how the aventail is raised and tied or pinned just above the turban...
Ottoman miniature showing Hamza (Prophet Muhammad's uncle)
riding a Simurgh phoenix, and clad in contemporary arms and armor
A similar armor set does indeed exist and may be the closest
to the ones worn by them both. This armor set belongs to the
Sultan Mustafa III (1717 - 1773) and shares many features...
Close up of the helmet compared
with another portrait of Murad IV
Interesting 2016 attempted, media portrayal of Murad IV
thou the helmet is larger, while the aventail seems shorter