9mm or .38spcl +P is the minimum I consider adequate power. I greatly prefer .45ACP, then .357 magnum. I've always considered 7+1 in my CCO SIG more than adequate for 99% of places I go. That 1% would mean carry an extra mag--or two. Most places, the 5 in my Taurus snubbie, 135gr Gold Dot +P short barrel, are just fine. If I'm going someplace where I think a gunfight may start, I'll have my M-4 with three extra mags of penetrator 5.56 NATO in the car.