up/insert  shots show the primers on the shotgun shells already discharged.  This means the shells had already been fired and would not work.  However, the point of the collar wasnt to shoot Lynn; it was  created by Amanda to create an explosion within the collar. The  reason it uses shotgun shells isnt revealed, but their not used as  shotgun shells or to shoot Lynn, therefore its not a goof that  theyre discharged. Possibly, Amanda used shot