RE: selling a gun?
you would have to check your local laws, some states are more strict then others. Generally with long guns (shotguns and rifles) i believe you can just sell it without any red tape. If you were selling to someone far away and you had to ship it to them, you would have to ship it through a FFL dealer to another FFL dealer where the buy lived and he could pick it up there. There is generally a nominal fee for the service. Selling handguns is generally much more complicated. Like i said i would check your local laws before doing anything