Most personal-protection aficionados have heard the Mark Moritz truism that the foremost rule of gunfighting is to “have a gun.” Indeed, participating in a gunfight without possessing a gun could be a painfully decisive inconvenience even for a master of unarmed martial arts. Many students of armed self-defense have also heard the many subsequent rules of gunfighting, those rules pertaining to choice of guns, calibers, and tactics, often paraphrased without citation. Which gun meets minimum requirements for you? The answer to that question lies in your own due diligence and the wisdom of others; I don’t have the expertise to offer an opinion.
To read where many of the rules of gunfighting originated, click here and here for an interesting pair of articles that give credit where credit is due.