an explosive primer designed for use with a fuse cord and an initiating device . the primer consists of a container , which holds the explosive , and a cap received on the open end of the container . the container has two lateral opposing cord tunnels which run the length of the container . the cord tunnels protect the fuse cord on the inside of the primer . the cap has two apertures which align with cord tunnels in the container . the cap has capwell for receiving the detonator . the capwell is pierceable so that a detonator can be inserted through the capwell and embedded directly in the explosive composition inside the container . in addition , the primer contains grooves in the bottom of the container and in the cap . the grooves communicate with the apertures and the recess in the cap and the cord tunnels to create a continuous conduit so that a fuse cord can be threaded therethrough to secure the cord to the primer and selectively position the primer in a borehole at the blast site .