http://www.lionsgrip.com/chickens.html
this is a fun website
Corn is 7-9% protein and is mixed into my feed too:
I use 1/3 unmedicated chick starter (org.)
2/3 of the following:
rolled barley
rolled oats (can use whole oats, is cheaper)
org. cracked corn (can use whole corn but it is easier on their gizzards to crack some of the feed for them)
millet (birdseed)
black oil sunflower seeds (birdseed)
wheat (the whole berries)
split peas
I don't serve it all - all the time. I do vary it but this is the basic thing I feed. The chick starter has soy and corn + vitamins, that's it.
They need meat scraps, soy, or milk for protein. Just peas isn't good.
Here:
http://www.ca.uky.edu/smallflocks/feed_ingredients/grains.html
http://www.ca.uky.edu/smallflocks/feed_ingredients/proteins.html
I love mixing my feed. With corn bantams will have a hard time if not cracked in my opinion, but the other things are OK for bantams uncracked.
If your soil doesn't have little pieces of gravel or rocks in it you might give them grit but usually they can find their own grit. It stays in the gizzard for at least a year.
Try to aim for at least 15% protein or thereabouts. You don't want to venture into the 12-13% protein range for layers.