just shoot the ball out.I have left mine load from year to year.I just put a cap on and fire it.if it will not fire,remove the nipple and put a little dry powder down the hole and fire.if that doesn' t work.
I have a home made ball puller.I took a rod and weilded a screw to the end(one of those screws that comes with a hanging lamp kit.the one that has wood threads on one end and metal threads on the other).just drop it down the barrel turn and screw as you put presser on the rod.make sure you get several turns befro you put the rod in a vise and pull slowly and steadly.

or carry it to a gun smith.??????????