a revolver is a good choice.
.38, .357, .44, .45ACP ... all the big rounds are good for personal defense.
I'd have to disagree with the "I have a gun" declaration. What you're doing is called "brandishing" a weapon. I think it's a bad idea.
Below is an excerpt from an earlier post of mine which explains why:
"Some people believe that a firearm brandished in a threatening manner without shooting can stop a situation. It would make sense since, statistically, over 90% of confrontations have ended after presentation of the weapon. But I'd still have to disagree with "brandishing" as a threat for several reasons.
The ability to shoot another individual under the right circumstance requires training as well as mental and physical discipline. The decision to shoot takes place over a split second. When you brandish a weapon you have placed yourself in a "mental" grey zone where you can't account for all the possibilities at once. What if the person looks you in the eye and faces you - he doesn't attack - but he also doesn't run away? You'll notice many criminals don't quite cooperate even when facing several officers pointing guns at them. What do you do then? I'm not saying this will happen - but it does happen.
At that moment he has the moment to read your body language - (fear? confusion? anger?) - until you actually face the situation you don't know in advance how you'll truly react. A common trick is to confuse your senses by begging for mercy and holding their hands up while obviously advancing on you - Your ability to empathize gets mixed signals because your mind doesn't see any clear reason to shoot - it's extremely difficult to shoot someone looking at you begging for mercey while he's crawling toward you - even if you KNOW he's faking.
Let's say this was a confrontation in the home and he runs away. Now you have a criminal on the loose who knows where you live and knows you have a gun in the house. Most likely he won't come back. But sometimes they do ... If I were in that situation it'd be hard for me to sleep for a weeks/months knowing that someone might return.
Also, if you draw your weapon without the immediate intention to shoot - you are depending on some instinctual "trigger" to allow you to shoot as the situation demands. If the "trigger" isn't CRYSTAL CLEAR the delay will cost lives.
e.g. You have your gun drawn on a burglar who approaches you slowly with his hands in the air saying "Let's talk about this, buddy." You tell him to stop and talk from where he's standing - but he keeps approaching slowly calmly saying, "I'm not armed. I just want to talk." In your mind you know he's probably just trying to close the distance between you two - You keep yelling at him to "stop." but he doesn't..... at what point do you shoot (if at all)? When he's got his arms raised in the air and 20ft away? 15ft? 10ft? 5ft? ....
I don't want to be in that situation - that's why I don't brandish."
http://www.tfproject.org/tfp/showthread.php?t=101330