Guns were made for 1 reason, to kill or seriously injure a person, so morally, all guns should be banned including plastic ones unless unless it's war and you're being invaded or to protect yourself. Can't eat dinner without a knife, it just happens you can kill someone with it...
[some history, too short to be complete but anyway]
Guns were invented to conquer castles to shoot the wooden gate in chips so the knights with swords could enter the castle (if not covered with hot oil or whatever). Gunpowder was too expensive in the beginning (to kill individual people with it). Before that even the Romans had their big catapults (don't recall the name) Further back in history David killed Goliath with a slingshot and before that people were throwing stones, and wood. Before people the monkeys did.
So from historical point of view, the gun is just the technological follow up of the hand. And yes, hands can kill (think martial arts).
- Many people in the world eat dinner with a spoon a fork only or just with their hands (too many unfortunately).
Some peaceful uses of guns I know of:
- in the mountains, shoot the snow to trigger avalanches before the trigger themselves.
- Guns were also used to guide ships in the dark/mist.
- Air guns (big automatic with compressor) to make noise to keep his cherry-trees bird free (applies to other fruits too).
- shoot a rope over a wall / building to climb it. (e.g. fire brigades).
- some medical injections are done with a sort of gun
- to get an elephant to sleep in a zoo => syringe(?) gun
Who can extend this peaceful list? (I think that after 6 pages we can agree that guns can be used by humans for lethal activities)