Abstract: An improved nipple, used with a percussion cap to ignite the propellent of a muzzleloader without significant ejecta from the nipple (back-flash), is disclosed. A check valve, preferably using a spherical actuator that is loosely retained within the valve chamber, is used to preclude back-flash. Use of a check valve and use of a relatively mild percussion cap (compared to primers) revealed a set of new problems that are solved by the disclosed device. Difficulty in removing spent caps, because of the lack of cap removing back-flash, was solved by flash chamber structure within the nipple adjacent to the cap. A tendency for the protective membranes of percussion caps to lodge within a nipple not having back-flash was cured by the use of an actuator retainer that directs the actuator to the side of the valve chamber during ignition. Ignition was improved by the use of a flash jet orifice and by the use of a directing actuator retainer.