I think the main problem was the triple 777 draws moisture at the point were it meets the nipple first cap dried the powder second cap fired the charge.Moisture seems easy to enter the nipple area with musket caps compare to cci mag. caps
I have found that the #11 cap has to be remove with the edge of a knife that would make a tight seal The musket cap has to be pinch to stay on the nipple and can be removed easy