A gun in a dream is often a symbol of aggression. If you dream that you shoot someone with a gun, you could be releasing feelings of anger or frustration that you believe you must repress in real life.
You may dream that you are carrying or gun, or that you shoot someone with a gun, when you are feeling threatened. The gun in your dream represents the strength that you have to protect yourself from the thing that is threatening you.
A gun is a masculine symbol, so if you are a woman and you dream that you are firing a gun, you could be developing the stronger, more assertive side of your personality.
A dream that you are shot with a gun can mean that you are feeling vulnerability.
If someone shoots you with a gun in your dream, you could be feeling a threat to your sexuality.