You're All Missing The Point
IF there is any moral to the movie, it isn't that guns are evil. It's that guns are simply tools and have no inherent morality.
1. The Dandies were intent on never using their guns to harm others, unless, as in the end, they have no other choice. They kept their gun use to a place away from the rest of society, simply researching and having fun with target practice.
2. All of the adults in town were terrified, even paranoid, of the idea of guns and gangs. Mr. Solomon, Clarabelle, etc. The sheriff also assumed guns = bad people. But this wasn't true. The Dandies were good people, something that all of the very same characters pointed out throughout the movie, until they discovered the guns. They were good kids, Dick was a nice boy, etc.
3. Despite being such "good boys", when a TOTAL ACCIDENT occurs, involving a SENILE old woman who's not entirely aware of her surroundings, they entire town rallies against them simply because they HAVE guns. Not because THEY have done ANYTHING wrong, only because they have guns. This is ironic because 30 or more well-armed police show up. Well-armed. This has nothing to do with the Dandies themselves, because they are considered good people, but the guns themselves, which by their PERCIEVED nature, have tainted them.
4. The Dandies are not only going out and getting shot because they want to deliver some coffee. After they lose most of their coffee, they continue. This is about an ideal. About freedom and their right to carry arms (hey, remember the Constitution everyone? Right to bear arms?). They are given the option to give up their "partners" but they choose not to. Why? Not because they guns have made them a blood thirsty gang (Huey first warns the police that they do not want to open fire and only wish to help Clarabelle to her annual visit) but because they have a right to not only their guns, but their choices. To give up their guns to the police would be to give up their rights, their ideals, their personal and private freedoms. It would also be accepting that they had done something wrong - but they haven't. They've injured or threatened no one, and their guns were neither, as far as the movie shows, illegal or dangerous to anyone.
5. The police, despite logical attempts to discuss their motivation and intent, assume that these people are dangerous. They don't ask why they carry guns, or if they are legally registered, or if the guns have ever been used against anyone. The line is simply drawn that guns make you bad, unless you're a cop, and then you can shoot people whenever you need or want to. Is that fair? No. Therefore, the Dandies fight both hypocritical viewpoints and police brutality. The police, within this film, have been condescending, sneaky, violent, and racist. This is part of the point. The ironic paradox of good people not being allowed to carry guns, while arrogant and tainted yet powerful individuals have them and may use them as they so desire.
6. Finally, yes. It is completely over the top. Social commentaries tend to be. It's (potentially) addressing the issues of gun control and police brutality. We had to be clear on the fact that the police aren't so obviously good guys, that the Dandies would die for their beliefs, that guns cause violence but only in the hands of people intent on causing it, etc. It was unrealistic.
However, I've seen lesser things happen - a friend was expelled from school because he came to class right after a hunting trip with his father. His gun was locked in his car, down the street in a public parking lot (the school is overcrowded) and yet someone saw it, assumed the worst, and reported it. In France, the Paris riots were sparked by police shooting a teen who was fleeing during a chase. Their was no proof of involvement in any crime, and he was shot in the back.
Point being, this isn't a movie about the evils of guns (though guns can definitely be used for evil - I think the police in this movie were doing more harm than the Dandies ever could have) or a simply coming of age story. It, at it's best, can be extremely thought provoking and important.