When I shot a flintlock I stuck a round toothpick in the vent while I dropped the charge & seated the ball. That kept the powder from being right up against the vent where a single kernel of powder could plug the vent. ThenI'd pull the toothpick out and prime the pan about1/3 full, but keeeping the prime charge well below the vent and to the outside of the pan. Ignition was often as fast as my caplocks.