Primer assembly

A primer assembly for use in the non-electric initiation of cap-insensitive explosives, especially of deck-loaded explosive charges by means of a single downline of low-energy detonating cord (LEDC), includes a percussion-actuated detonator seated in a cavity in a high-energy primer, and an explosive coupler in which a coupling explosive charge, housed in a plastic connecting block, is in initiating proximity to the detonator's percussion-sensitive ignition charge and sufficiently close to a cord-receiving perforation or conduit in or adjacent the primer as to be initiatable by the detonation of LEDC threaded therethrough. A preferred connecting block has a U-shaped channel for engaging the detonator, and a connecting block arm for attaching the block to the primer. Preferably the explosive coupler is seated within a block-like cavity in the primer.