Where are you housing them now? They should be in a coop and run with 4 s.f. in coop and 10 s.f. in run per bird. If they don't have that much space available, that could be the reason why they are pecking each other. Generally, chicks who have enough room, are not kept too warm, and who have plenty to do, and enough protein in their diets do not seriously peck each other.
