CommentStreams:Ebf9843834335faa61e9055c513affc6
From The Lost Media Wiki
That's totally fair, I myself would have probably only used those sources as evidence of the "popular belief". In all honestly, though, I wouldn't put it past them to use it for practice (especially since their original plan was really elaborate), but I think they actually practiced with real firearms. Really though, anything's possible with Harris, he was a very disturbed individual.