First thing, your barrel is either 24" or 26" if it is a .50 cal, not 28".
Knight sabots may work, but they can be very tight in some barrels.
I would imagine that your Clean Shot is at least 5 years old (APP has been out around that long) and is probably a solid mass in the container. You can gingerly break that up, but it has probably absorbed too much moisture to have any consistancy. If you are just wanting to make some smoke and plink around, it might be alright for that.
If you are looking to work up a hunting load, do yourself and the deer a favor and get some new powder.
No problems with the 209 primers or the bulllet weights as long as you get a good powder.