Never, ever tell anyone that you are carrying a firearm or show your weapon to scare someone into leaving you alone. It is called a "concealed weapon" for a reason. Before you show your gun to anyone, make sure that you would be legally justified in using it in case the person doesn't back down.
Let's say that I'm a bully and I need my ego inflated and for whatever reason I decide to get in your face as you are going to your car, or into a store or where ever. Instead of being a coward and running/walking away, you unbutton your coat to display your firearm and you calmly say to me: "Look. I don't want any trouble." Or, maybe you don't say anything at all.
The mere sight of the gun turns me into "Mr. Nice-Guy" and I walk away but I note that you were carrying a stainless steel revolver or a blue 1911 or a Glock or something that might have looked like a Glock (say, maybe a S&W Sigma).
I also note where you are going and as soon as you are out of sight, I call 911 and report that some crazy man was cursing at me and pointed a gun at me. Pointing a gun, even an unloaded one, at someone without justifiable cause is considered aggravated assault.
The police now have a report of a nut with a gun. Within minutes the police arrive on the scene, confront you and find your firearm which matches my description of your gun. The tables are now turned -- you are now the bad guy and I am the innocent victim. In their eyes part of my story is already true -- I've described you and your gun. How else would I know that you have a gun and what it looked like unless the rest of my story is also true (that being that you pointed the gun at me like I said).
You are arrested for aggravated assault and if convicted, most states and communities require a mandatory prison term.
Or, let's say that when you flash your gun and I don't turn into "Mr. Nice Guy". Instead of backing away, I get in your face even more and start screaming at you: "What are ya gonna do? Shoot me? Go ahead *&$^@($^&, shoot me!" and I start shoving your around. Unless I had a deadly weapon (a knife, a baseball bat, even a screw driver) which I could use to seriously injury you or even kill you with, you would not be legally justified in firing your gun at me just because of verbal threats and some shoves or punches. However, by showing me your gun, you've now escalated the situation to the point where I just will not leave you alone because I know that you will not shoot because of the serious legal trouble that you'll find yourself in.
Whatever the situation, never show your gun unless you are prepared to use it and can legally justify using it. Otherwise, it can create more problems than it solves.
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Share what you know, learn what you don't -- FUD.