This is because gun control laws arose from white middle class fears of black people. Conservatives actually wrote the first gun control laws. Read this article from Reason magizine about gun control, it “turns on its head the modern liberal’s conceit that those who side with gun control necessarily side with the people.”
Personally I have always been confused why liberals favor gun control so much. It should be obvious that minorities are often members of the population that are most vulnerable to violance of racist majorities to include law enforcement. Blacks time and time again throughout American history have been able to defend themselves against the likes of the KKK because of the universal right to bear arms. More than this, the right to self defense is a civil right. How can someone support “civil rights” but not support gun ownership?
A true liberal should be in favor of gun rights. So should a true constitutionalist. Only a person with no ideology at all can favor the curtailment of gun rights because there is no philosophical school of thought that can justify gun confiscation other than total authoritarianism.