Some of this "over exuberant" warfare is often the result of too little space, and too much bright, white light. Chicks, raised by a broody hen, spend a lot of time under her wings, in darkness. When she does take them outside, they are busy with investigated the world and eating. Not much time to get fussy with each other
In the brooder, bad pecking behaviors can be toned down by keeping the environment darker and a heat emitter or red bulb seems to help, in our experience. Bright ambient light from the room they are in can also effect them. High protein feed of 24% is often enough to discourage cannibalism. Finally, space. Boredom and over crowding are not good things.
Just some things to evaluate and look over in your own system. Best wishes,