It’s rather a play on words that leads to irony and thus comedic effect. (More a-ha than ha-ha)
Anti-gunners complain of gun violence when people commit crimes. So they attack the right to keep and bear arms (guns) rather than bad behavior. This in turn is trying to use state sanctioned violence to attack guns, thus becoming the very thing they swore to destroy. Maybe I should have added that meme as a second panel. I prefer single panels whenever possible, however.
