That's the sort of comment you should color purple, lest you lead people to think you are an idiot.
Why? It might be mythical from a production standpoint... but I don't see why a scientist couldn't really make a 100% plastic gun if they wanted. They have been developing plastics/composites that are 5, 10 even 15 times stronger than steel for awhile now.... There may not be a market demand for it right now... but that doesn't mean its impossible to do