dI concur entirely. Assuming your end is entirely on the up and up, consider your own protection. What happens if someone agrees to help you. They go pick up the weapon as your representative and turn around and use it in a crime...are you going to then go to the authorities and try to convince them that your selected representative was a thief or felon? You should make the time to go pick it up yourself, or tell the authorities to dispose of the weapon for you.
I hear you. There are all sorts of forms that I will have fill out including a notarized one for the agent. I assume that the agent would have to be fully identified.