James Yawn describes a method of preparing KNO3-sugar propellant that does not require melting either component, but just heating an aqueous syrup of mixed sugars, separately warming the dry KNO3, and then mixing them off the heat -- a lot like BP blender rockets conceptually. In fact it's JUST like blender rockets except that both the fuel & oxidizer dissolve in hot water instead of just the oxidizer. Mixed sugars such as corn syrup and sucrose are used to inhibit formation of large xtals. The product is said to burn almost as fast as propellant made by cooking the complete mixture.
However, the resulting mixture is not so plastic as to be rammable into a case, or cast as a slurry as with blender rockets. Rather, he rolls it into a cylinder with a core, then primes it inside and out to form a constant-rate grain that he slides into the case. It's not clear from his instructions (or what I've read of them so far) how long after mixing the material remains plastic enough to do this without reheating -- and it's heating the complete mixture that I wanted to avoid -- and then how long it takes to dry and harden in place.
Has anyone used this for firework sky rockets? If I wanted to turn it into a progressive burner with a nozzle (apparently eliminating caseless from consideration), is there another way to inhibit the outside surface while allowing a fit loose enough to get it into the case to begin with, but tight enough to resist the pressure during firing? Or, with a catalyst, might caseless with no nozzle be fast enough to allow it to lift go-getter style?