Tony,
Welcome to TRF! Glad to see more and more new people like yourself...and we especially like to see great projects. But I'm sorry to tell you that we don't discuss EX in this forum for various reasons....it needs its own category

Please do not think that we don't want you in here because you are completely welcome and there are tons of knowlegable people to talk with and get help with. But EX motors are one of the things we do not discuss. I am also a member of the
www.rocketryonline.com forum and they have a amateur/experimental section of their forum that is the perfect place for this post! But since I am talking...it does sound like quite a hefty motor...but may I reccomend something? It's obvious that you are doing a variant of the common "sugar" or "candy" propellant...the only really big difference is that you are using Potassium
chlorate and that's NASTY stuff...you don't want to mix chlorates in with rocket propellant. You may be getting it confused with Potassium
per chlorate...but that's not that much better (there's only one reasonable formula that I know for that). For this type of propelant you need Potassium
nitrate which is commonly used in the sugar propellants...but also, sugar is not only the fuel, but the binder in this type of propellant (it's a process of melting the sugar and then mixing in all of the other chemicals in it). You don't need the epoxy....however some people are working on formulas that replace the sugar with epoxy and other chemicals, but epoxy and sugar usually do not go together. It's one or the other. Some epoxy propellant formulas do have a VERY small amount of sugar in them for fuel though...but the general rule is either sugar for fuel and binder OR epoxy+some other things you'll have to find out for fuel and binder. Try
www.nakka-rocketry.net for TONS of info on sugar and epoxy based formulas, motors, and A LOT of other excellent information. Lastly I noticed that you are jumping right up to the big 4" motor....I reccomend getting it down with some small test motors first and then moving on up (aw darn...gotta make more motors

). Also, the Durhams would do OK in small motor nozzles, but for 4" you're looking at phenolic or graphite nozzles. Well I hope the info helped and try
www.nakka-rocketry.net, and this post would be great for the
www.rocketryonline.com amateur/experimental forum. Hope that helped! And once again welcome to TRF...now bring on the pics and the questions about your rockets themselves and
certified motors!