I have been using Chex rice cereal from the minute that they came out.
From the beginning, when I just started with the gluten free baking, I made only bread crumbs . I tried many recipes and made huge breads that were edible proximately for two days. Rest got hard like stone. You could break your teeth on them. I dried them up, and made bread crumbs with the help of food processor. Today, I'm a "professional" in baking, and I have a problem with bread crumbs. I don't make them anymore. So I have been using Chex.
I will run 1 and half box of Chex cereal in the food processor. It will turn to flour. Then I will crunch another half of bag with a rolling pin, or meat tenderizer. I will mix everything together, and store in a steel container.