I carry a loaded .45 most every day and I have a very good idea of what is and is not self defense.
If I pursue someone off of our property it’s hard to make a case for self defense.
But if that person you are chasing off the property tries to wrestle (rassle) your pistol away from you, and as you grapple he gets shot...that IS self defense. And it doesn’t not become so, simply because you had the temerity to arm yourself when you went out to confront him.