Paul, A good start would be to see the book The Art of Flintknapping which is available from Track of the Wolf (www.trackofthewolf.com). This book is mostly about making arrowheads but they do have a section about knapping gun flints. Take a look. Shoot sharp's the word, Mike
That is good advise, it is very simple but a picture or two in a book would explain better than two pages of text, spalls are the easiest way to start, this was what was used before the French developed the type we now call English flints, there is a pretty good bit of info on making them in "Colonial Frontier Guns" available from TOW it is under 20 bucks I think, and is also one of the better books on trade guns and French hunting guns if they are of interest, a lot of book for the $$$
There is a fellow named Rich Pierce who makes flints here in the US that might be of help. He posts on another site [American Longrifles]. It seems to me to be not worth the effort, even the native Americans used flints shipped in from europe by the thousands--and they were adept at chipping flint! But if you have a ready source of material and the time it ought to be fun to try. I think preparation of a "core" from which to flake off blanks is one critical step.
I think preparation of a "core" from which to flake off blanks is one critical step.
If you have to buy the raw material and have it shipped it is a better deal to just buy them from Rich, Spalls are easier to make as most any chunk about fist size or so will yield a few, it is kind of fun to learn how to make them, like projectile points, I fiddled with that for quite a while till it cliked then made a hundred or so and haven't made one since, it is a nice part of history to experience if nothing else.