Premium Feather Member
Could also be a JG, but really it's a tough call until they're bigger. They will be larger than a Production Blue. They usually have a willowy cast to their shanks too. Are her legs greenish at all?
I don't really know. The yellow is clearly there all the way up the legs:
This is her photo at 3 weeks:
BTW, we don't seem to be using the same terms for breeds here.
In Welp's catalog this is a Production Blue. They have very clear red leakage.
This is their Blue Plymouth Tint:
This is their Blue Jersey Giant
And they have no photos of their Blue Plymouth Rocks but the dark head seems to be consistent with Blue Rock photos from other hatcheries.
Too many hatchery designer breeds/varieties!