Several of the "bad behaving pets" type shows on TV stress how important it is to keep animals "busy". Boredom is probably the number one cause of bad behavior.
Try putting the comics section of the newspaper on the bottom of their enclosure. Sprinkle a small amount of food on the paper. See how long it takes for them to turn it into compost.
Do you have a weed in your yard that you think the chicks might be interested in? I pick dandelion blossoms (enough for everybody to get one!) and drop them in the box. If you can't find that many blossoms (lucky you!), rip the blossoms into pieces prior to dropping them in. They will start squealing "I have a goody" and try to run off to eat it, which of course causes everyone without a goody to run after them. I don't think they ever learn to keep it to themselves when they find goodies, lol.
I buy the bagged hay for Mr. Bunny. A few seed heads become chick feed. Just today I shredded two seed heads. When they are older I will grab several seed heads and break them into small sections.
My son donated a small "bouncy ball" for the chicks. I think they ingore it. Soda bottle plastic caps in differnt colors are interesting if they have food sprinkled in them. They must be, I throw them away when the caps become crusted with poop!
My point is: give them something to do other than peck each other!
Spend more time with them. I crafted a brooder box out of three large boxes. Much duct tape later, I can get inside with the babies. They love pecking my wedding ring, so I'm trying to train them that if they sit on my knee, I allow them to peck my ring all they want. This also allows me to teach them not to peck skin so hard. I sit quiet if they peck my ring or clothing. My skin earns a jerk and an "ouch!" This works with kittens and puppies. I'll let you know if these babies become more gentle than my other chickens.
Lots of luck!