A primer assembly includes a head loading assembly including a frontward throughbore, and a rearward throughbore having a stop. A closing plug assembly includes a conically bored open frontward end and an open cylindrical rearward end including an outer flange between the frontward and rearward ends. The closing plug assembly is press fitted into the head loading assembly frontward throughbore. An ignition element assembly is press fitted into the head loading assembly rearward throughbore. The ignition element assembly has an ignition element portion that bears against the stop. The closing plug assembly and the ignition element are located to be captivated by threading a flashtube into a head loading assembly threaded portion.