At no point is free range "safe".
While a 12 week old is less likely to be killed by a hawk, it happens.
Predators are out there, see them or not. I lost two full grown, hen turkeys to a fox that had never been here before.
I've seen an owl decide to kill a grown hen but be unable to do nothing with it.
In a truly free range situation, you lose stock. That's the way it is.
Six weeks is something a hawk would fine proper prey sized to remove in most breeds.
It's best to design hides, trim bushes to provide broad dense shelter, provide netted space and other safe zones - to provide SHINY objects to deter hawks like hanging CDs/DVDs.
Those help. But there is NO true safety for a free ranged animal, ever.
If you want safety you build a big, wire enclosure, with a top and dig wire and small mesh and hope.