YOu are going to need a billet made of elk horn or something else that is both hard, but not as rigid as a steel hammer to throw those clam sized chunks. Hit that preform with a steel hammer, and all you will get will be are smaller chunks. You probably found that out. Flint fractures at a 270 degree angle. the secret is to hit the rock preform at the right angle to send the force along the right fracture line. It takes a lot of practice, even with a tutor sitting next to you, and showing you how to hold every thing correctly, and how to hit the rock. You will want a heavy piece of leather to cover your leg, and at least one leather glove on one hand to hold the rock so you don't get rock splinters in your hands and legs. You also want to wear eye protection. You will still occasionally git shards in your skin- the neck and face, but also forearms, and hands. Check out the sites suggested and read and watch everything available. Then see if you can find a flint knapper in your area of the country that is willing to help you learn. There are a couple of " knapp-ins " held each year around the country, where people sit around and make little rocks from big ones. They are great folks, and some have become very skilled and turn out awesome points, and other tools. YOu can also pick up shards for your flint and steel kit at these events. Dixie Gun Works also sell flint shards for this purpose. You can check other suppliers, like Track, or log Cabin, or Cains, etc. to see what they have.
