I agree that shipping through a FFL is your best option in general. Consider the legal advantage also...you turned it over to a FFL and the FFL took upon the responsibility of shipping the pistol/assault rifle/etc.
For me...I recently shipped a pre-ban ASSAULT WEAPON
to a retired LEO in NY. My wife and I stoped by the local USPS and after waiting in line for twenty minutes approached the counter and declared that I had a firearm (long gun) I wished to ship. The postal employee stated that I must show him that the firearm was unloaded prior to him shipping it.
Just about everyone in the post office held their breath and seconds stretched into minutes/hours (temporal time distortion!) as I pulled my black rifle out of the box, locked the action open, and displayed the empty chamber to the postal employee. He sneered and recoiled backward as I moved the rifle closer to him so he could view the empty chamber.
After he gave me the OK to repack it I elected to close the action for shipping and slapped the bolt/carrier release on the side of the receiver. The sound of the bolt/carrier group slamming home is classic and music to my ears. My wife rolled her eyes and smiled at my animalistic display of freedom and independence.
The postal employee then suggested that I take my rifle to UPS or FedEx for shipping. I thanked him for his suggestion but insisted that the USPS ship my rifle. :P