I shot 777 in my Encore 14" barrel for years with a 250grn Shock Wave. I would use the 777 loose powder and 80 grns. I have taken whitetail out to 80 yds with it and all pass through shots.
I cut a rifle muzzleloader down to 14" and used a rifle forend with the tension spring to hold my ram rod.
Good luck with your muzzleloader.

Mike

You don't quit playing because you get old, You get old because you quit playing.