For that age that's not too crazy.
Like @Pyxis said could just be exploring hormones. Lots of times the cockerels are ready to mate before the pullets are ready to let them.
Are there actual signs of physical abuse on your hens? If not I'd say there's no real problem.
How are you so sure?
Just because they are pecking or grabbing the back of their necks and the pullets are squaking doesn't mean it's anything out of the norm.
I just got 2 new pullets and a rooster last week. The coop door is usually opened up by noon but today was the first day those 3 left the coop.
I think it just takes them some time. I know when I put my chicks in the coop around 10-12 weeks late spring it took them over a week before they...
I have 8 pullets from late March and at least 5 of them are laying. Just by looking at them I can tell one isn't anywhere near ready but 6-7 of them I think will be laying in the next week maybe 2.