If you put a non-barred rooster (and non-dominant white) over a barred rock, you'll get a black sex link. I don't think most Icelandics carry barring. You can clearly see saddle feathers on the barred birds in the pics, not the specific birds the OP is asking about as they've apparently already identified them as males.
Pure barred birds are easy to sex. If only one parent is barred, then they will all have dark barring like pure females. The way the barring gene works, a barred hen can only pass her barring gene to her male offspring. If the parent roosters aren't barred, than any barred chicks can only be male. It is genetically impossible to get a barred pullet from a barred hen/non-barred rooster pairing.
