guns are guns are guns. you shoot someone with a gun and they die. It's not a matter of the size of the bullet, if you get shot i guarantee you will go down. It's not a matter of caliber, it's a matter of proficiency.
handguns are quite useless in nearly any match up. great for conceal and carry if you are that kind of person. but for home a person should have something bigger.
if you had good bullets, that wouldn't do stuff against 5 other people. If you had an assault rifle or something of the sort however, things could turn out differently.
Ok say if 6 people had the same gun with the same bullets. If 5 people teamed up against 1, who the forget do you think would win?