We only have 7 chickens fully grown. We only let them out while we can watch them. We have hawks and even owls in the evening will fly over and hawks have even swooped down before. I believe 7 weeks old they would be dinner quickly.
We stay with ours, we only have seven, because we have hawks all the time flying over and have even swooped in before. So, we only let them out while we are out with them. I have neighbors who have lost some while not watching them.