RE: best powder to use
welcome bear6. I too am fairly new to muzzleloading and shoot a cva optima. I agree with cayugad with regards to the hornady xtps. I have used both the 250g and 300g with crushed ribbed sabot and my cva likes them. I have been shooting 777 pellets just to get acquainted but will use 777 loose for the first time tomorrow.
Enjoy the rifle and be safe.