ebay unusual stock question

I note that forum advice on the unusual stock on ebay was that if ATF catches you with it--Dooms day. Would not the situation more likely occur if you were caught with it "attached" to a Luger. What about all of us who have Artillery and Navy stocks displayed with attached artillerys and navies and also own detached 4" bl Lugers? I believe that "attached" is the key word here----wanna bet that after the seller was "scared off" ebay; a shrewd collector[probably one of us] contacted the guy and bought it cheap?