It's largely a wedge issue that is used to fire up support for one side or the other.
Aside from constutional issues, I personally don't support gun control because I don't like the idea of telling people what to do. If someone isn't hurting anyone then let them have their gun. It's the same reason I do not support the drug war.
In fact, I would argue that we could make a lot of progress in stopping gun violence by changing our drug laws but that is a different topic for a different time. Upvoted and followed.