98 2 dated nov 9 1997 application_number US 10605298 A description fig2 and 2b depict a prototype embodiment of the current invention as installed in an in line muzzleloader 10 back flash check nipple 40 is screwed into the receiving threads of breach plug 14 percussion cap 30 is seated on the anvil 49 of nipple 40 when striker 16 strikes percussion cap 30 the explosive material of the cap is compressed between the cap shell and anvil 49 thus igniting the primary flash the primary flash is directed into flash chamber 48 the pressure of the primary flash moves actuator 47 away from valve seat 45 the primary flash then travels past actuator 47 and retainer 46 within valve chamber 44 and is directed by jet orifices 42 into a high velocity jet that ignites propellent 18 the preferred jet orifice 42 preferred retainer 41 and the preferred flash chamber 48 are discussed below the preferred actuator 47 of the present invention is a metal sphere smaller in diameter than valve chamber 44 too large in diameter to pass into flash chamber 48 and of such a size as to be capable of forming a good seal or with valve seat 45 the preferred valve seat 45 of the present invention is capable of forming a good seal with actuator 47 after ignition of propellent 18 has been effected and it has been found that a smooth conical surface inclined about 45 degrees to the major axis of nipple 40 is satisfactory an included angle of about 90 degrees if the included angle of valve seat 45 is too large then actuator 47 will tend not to seat properly too small of an included angle will tend.