As far as a comprehensive list for everything out there for guns, that is time-prohibitive and ends up limiting creative freedom as we could easily miss some kind of weapon and then people think "Oh, it's not on the list, so I can't use it" if we come out and say that this is our comprehensive list.
The guide was created to cover the primary weapons that people use in their submissions. As other systems are used, if they prove popular, we'll look into giving them a note in the guide. But right now, the guide covers 90-95% of all possible instances. When in doubt, ask a Factory Judge or RPJ. It's what we're here for.