Press release and link to complaint here. On a quick read:
1) Venue is in NY since Everytown is located there? Federal venue, proper location of a suit, generally keys upon location of the defendant, not the plaintiff.
2) They tend to confute the definition of a firearm (which includes firearms that may readily be converted to fire a cartridge) with receiver (which has no such inclusion). The readily converted language is there because in 1968, some juveniles were making guns by converting starter pistols to fire .22s.
3) They don’t to be able to define, any better than ATF has, the point at which an item becomes a “receiver” on its trip between a block of metal or a piece of sheet metal and a finished receiver ready to receive all the other parts.
4) This “ghost gun” stuff is a continuation of a trend dating back to the early 1970s: invent a cute name for a type of gun, and move to ban it. First it was “Saturday Night Specials,” then “Snubbies” (snub nosed revolvers), now “Ghost Guns.”