When a flame from an ignited flammable gas enters the conduit and ignites the explosive pack, the bullet is propelled into and frictionally engaging the inlet end of the conduit body such that {HEAD ~ an internal passageway} in {TAIL ~ the inlet end} is substantially blocked to prevent the further propagation of flame upstream into the conduit 
When a flame from an ignited flammable gas enters the conduit and ignites the explosive pack , the bullet is propelled into and frictionally engaging the inlet end of the conduit body such that { HEAD ~ an internal passageway } in { TAIL ~ the inlet end } is substantially blocked to prevent the further propagation of flame upstream into the conduit
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