Greetings.
I recently traveled a couple hours away to pick up a pistol and accessories to save some money on shipping, gas, FFL fees and just to have it faster.  
Their was a whole package agreed upon which I have a couple pieces of proof of.  When I picked it up he stated some of the other accessories were in storage and his wife had the key and she was out of town until the following day.  He told me he would overnight the extra stuff Wednesday so i'd receive it Thursday.  He tried working out some way to insure I would get it like me post dating a check, but I had no checks and went out there with cash. Many factors about him made me feel comfortable with trusting him along with the couple times he tried to work out a way for me to beleive     he would send my stuff.  
Well, Thursday went by with no package.  I had emailed him once the day before and oonce that day to ask if there would be a grip screw in with the extra pair of grips because I had snapped on in half screwing it back in the grip hole.   No response.  I called him on Thursday to ask over the phone about the screw.  The home number he gave me before we met led to a lady telling me I had the wrong number.  I tried his cell number which worked but he didn't answer.
If the package doesn't come today I think i've been cheated for sure.
I know his name, address, cell number, and where he works.  I also have proof of what all I was supposed to get.  What is my first step of legal action?
I appreciate all your help and advice.
Thank you for your time!
Take care

First hope all works out, second post dating a check doesnt do anything. That is simply an agreement between you and the payee, the bank will and can cash it anytime it is presented....