[finnman69]

Are those Cast Boosters?

http://www.explomo.com/commer.htm

UEE Cast Boosters are high energy explosives, designed to initiate blasting agents. They can be initiated by detonating cord and/or no 8 detonators producing a high velocity and energy detonation. UEE Cast Boosters are cylindrical and dimensioned in accordance to their weight. These boosters are longitudinal perforated to facilitate their connection with detonating cord or detonators.

[Petronski]

I do not know. I hope we have as many FR explosive experts check in here, so we can develop a theory on that.