Since you've already been pedantic here, I'll note that a 'shell' can also consist of pellets fired from a shotgun round, which are still 'inert bits of metal p

Since you've already been pedantic here, I'll note that a 'shell' can also consist of pellets fired from a shotgun round, which are still 'inert bits of metal propelled from a barrel' but for at least a traditional round (e.x. 'buckshot') do not detonate later...