MJOLNIR mark VI helmet

Hey people, I have been practicing drawing MJOLNIR armor for a while now. My goal is to eventually get good enough at it to draw without reference. I am getting better at drawing the Mark VI helmet so I decided to see what others think. I posted the picture just to see what you guys think. It’s nothing much but I would appreciate feedback or maybe some tips.
http://i.imgur.com/uIlJJ.png

bump
need feedback!

Looks good, I would like to be able to view it as a bigger picture though. For some reason I can only see it as a thumbnail.