Having no AK Xtreme Metal Steel actually, I've tried to use Gun Metal but that was too dark. So, looking in my stock I found some Gunze Steel (an old can) and paintbrushed it on the 21UM. For the 21MF, I will wait until the Jemeppe expo, mid of may: I've reserved AK products on a seller site.
Anyway, after having painted steel, I've set the decals (Slovakia). Decals are from the kit and are of excellent quality