belong to a gun club and had some proficiency.
You also need someone who would be willing to do it and either doesn't care if he gets blown away after he accomplishes the task... for someone else, or, he's young and dumb and doesn't realize that he's a patsy who will have his head blown off.
They had pros to assassinate Kennedy, but it took perhaps the 3rd or 4th backup to actually kill him.
https://youtu.be/4oVpt_I9iQQ