In an at-will state, if the HR department called you in and told you that they found out you owned guns and said their policy is not to employ people who own guns, would that law suit work in your favor? I don't know, because IANAL. But I'd like to know.Employers can't stop you from owning a gun. They can stop you from possessing one in their workplace. Same as I can say you are not allowed in my home with a gun if I wanted to.
Rights exist but sooner or later peoples personal rights overlap