Maybe not widespread, but my grandfather's hunting club followed heightened trigger discipline back in the 60s and 70s. Most of them were WW2 vets though so maybe that's relevant.
Gun control is just another tool for suppressing disfavored minority groups. Black leaders during the civil rights movement knew that they needed to be armed; MLK Jr. was denied a permit for a pistol--he applied for one despite advocating for non-violent action--but his bodyguards were always armed. The Black Panthers knew that being armed was the only way to make cops follow the law, and that scared white people so much that Reagan passed the Mulford Act in California. The very first gun control laws in the colonies were laws banning black people from owning firearms.
This will give you the details but basically Malcolm X said that the shitty leader of the Nation of Islam shouldn't be the leader and then he started to get death threats so he felt he needed to protect himself. This picture, I believe, is him at his house.