The riddler
... Is a nickname my Dad says the gun was called back in his day, though we are Irish, so for some reason it may be a regional term.  Has anyone else heard of this nickname for the Tommy gun?86.46.249.193  

The list is certainly not all-inclusinve and is not intended to be that.  Since your father uses the term, it's likely that others did as well. Often these things are started in or perpetuated by novels and comic books.  At any rate, if you could establish that it is a noteworthy nickname, then it'd probably be appropriate to add.