Let's see if I can spot (some) of the problems
1. tripoli doesn't allow PVC motors
2. tripoli doesn't allow micrograin (e.g. pressed motors)
3. compressing grains of any type is inherently extremely dangerous (one of the other micrograin motor packing procedures actually encouraged to do it BEHIND a bunker, with full protective gear on. the people were stationed behind the earth berms)
4. ANY motor could energetically disassemble, if the nozzle plugs. Dry, compressed fuels are especially vulnerable to this as there is little in the matrix to keep it together.
5. using a grinder, especially without a sparkproof motor. is a horrible idea with ANY oxidizer. Don't become complacent because it's not so bad on this one.
6. Spent shells probably aren't good for motors as they have been exposed to high temp & pressure, are only designed for single use, and you don't know the strength of the case
7. tripoli doesn't allow steel motor cases
However, we do make sugar based motors using a completely different technology. Not many people do because they lack specific impulse. More common are AP based motors. You need to gain access to the research part of the forum to see how.
At any rate, abandon this! if you want to make motors, join tripoli, get your L2 and find a mentor. You can avoid a lot of expensive and potentially deadly results. Making motors is not a benign act - there are dangers, but also safety procedures to mitigate them......
Good luck