My old Benelli M1 would not digest the Federal tactical loads well until I had about 1,000rds through it. A buddy's ate them from day one. Make sure whatever you decide to use for defense loads you run a few hundred through your weapon from various shooting stances. You don't want to be in the middle of shitting your skirt when you realize your S&W MP doesn't like those Gold Dots the guy behind the counter, who generally doesn't know shit, sold you.
Whatever you decide to use, make sure you shoot it enough to develop muscle memory. When the SHTF, minor motor ability is the first thing to go out the window. You will also begin to dig deeper into your mid-brain. Program your computer to do the right thing before you need it. You will never rise to the occasion, only sink to the level of your preparedness. --The 7 P's --