Question about shipping guns to an FFL

Why do some ffl's not allow shipments to come to them unless they come from another FFL?  

I was talking to someone tonight that I am going to ship a gun to and they had spoke to several ffl's and all of them said I would have to have my FFL ship it to them. 

You don't fill out a 4473 to ship/sell a gun. He simply logs it in and then logs it out. It means nothing or am I missing something?

A felon could ship/sell a gun to someone. The possession of it (by a felon) would be illegal but is it illegal to buy a gun from a felon?

I don't know their reasons, but I prefer to ship by USPS as opposed to the troublesome UPS/FedEx.
USPS must go FFL to FFL/Manufacturer/Dealer on USPS Form 1508.
It is hassle free and much cheaper for the same insurance protection.
Jerry

Oh wow!  I have sent four guns through my local USPS and never needed anything except a copy of the destination FFL. In fact they told me if I were shipping to a well known place like Ruger or S&W, I wouldnt even need a copy of it. 
Never heard of a Form 1508 until now.

Individuals are restricted from shipping handguns through the post office, although some big companies like Taurus tell you to do it if shipping a gun to them for repair. The reason  many FFLs dont want to except guns from individuals is the fear of getting stolen guns at least by going into a FFL, they have to produce valid id to be able to transfer.

I shipped a .40 Ruger auto a few months ago to a gunbroker buyer in FL.  I didn't realize at the time that handguns HAVE to ship overnight here in PA and the price to do that through UPS was $116.  You have to go to a UPS depot, you can't ship from a "UPS Store" broker, which was another PITA.  I had to ship it via USPS through my local FFL as you cannot ship USPS (only $25) unless you have a FFL.

All I needed from the dealer in FL was a copy of their FFL which I verified as valid via the BATFE website.  All they needed from me was a photocopy of my PA State ID (driver's license).  Then the FFL and the guy I sold it to handle everything else.  I was surprised I didn't have to "sign anything" effecting the transfer of the pistol.

Not sure how it works shipping in and between other States.

It's up to the receiving FFL if they will accept from an individual as long as a legible copy of their driver's license is enclosed.  USPS requires a 1058 filled out by an FFL, but do not require any other documentation such as copy of the license.