Hi there. Impressive work so far! I've just noticed that the screen used helmets have a different lens shape to the Black Series. Look at the centre corners (where the eyes meet) and you 'll see that the screen used ones have an almost vertical angle change where the Black Series eyes shapes taper to a point:
http://img09.deviantart.net/8fc4/i/2016/210/a/3/costumes_of_rogue_one____stormtrooper_21_by_topgunsga-dabuv3u.jpg
http://target.scene7.com/is/image/Target/50702022_Alt02?wid=520&hei=520&fmt=pjpeg
https://www.google.co.uk/search?q=black+series+helmet&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiX8ujimdvTAhUfOsAKHTUdDqcQ_AUICygC&biw=1920&bih=950#imgrc=V-vs5d9tNKJRwM:
Also it really looks like the frown is slimmer on the screen used. This kinda puts the whole screen accuracy/authenticity of the Black Series bucket in doubt! Whatchthink?