That's what I would do before you get a full on cannibalism out break. A personal experience with the production reds.
The pecking ends when the mean bird dies. Next time you water the birds watch to see who drinks first. See who stands off to the side and waits. Are the ones that wait missing the most feathers? suspect #1 the prettiest one. Literally your birds are trying to eliminate competetion. In nature they would run off the other hen but confined hens have no where to run. It is a slow death so get rid of your bully/bullies and keep the sweeties.
The reds I had did this to my buffs and if i had known then what I know now I would have culled every red from my flock the day I saw the first buff bare back. Because two days later bare backs became bloody pecked to the bone backs. When the reds were culled all pecking stopped. Also free birds don't peck.
Pecking ends when mean bird dies - got it... I'll have to watch them on the roost for a while over the next few nights and see if I can find the mean bird. I know she's in there because their is one hen that tries to peck me sometimes. It's just identifying her is the problem