So, this is a question I have not been able to get a consistent answer to. I know that UPS, FedEx both require that handguns be sent through an FFL dealer. The question I have is this. I send a handgun to a custom gunsmith for work. It is shipped from my local FFL. He is telling me that the handgun then has to be sent back to him, run through his books, I have to fill out the 4473, pay for a background check, and now in Colorado, have a 3 day wait period to get my legally owned and obtained property back.
Is is possible to have the gunsmith return it directly to me? I know if I send a handgun off to the manufacturer for warranty work, they can send it directly to me. I am confused.

An individual has no way to send a handgun to a gunsmith any more since UPS and Fed Ex changed their internal rules. Evan a dealer cannot ship through them unless they have registered as a dealer with them.
And an individual cannot mail one. So, the old rules are invalid now, and you have to go through a dealer both coming and going. Sucks, but it is the liberals doing that to law abiding gun owners. Your dealer, is ripping you off because all he has to do is make a phone call; and I know some charge big money for that. So, no, that gunsmith won't and can't return it to you, since it can't come from you in the first place. Catch 22.
Long guns, yes. You can mail a long gun. USPS.
I mail a lot of jeep axles. No guns.

It’s not the law, it’s internal rules made at fed ex/ups.

The post office is great for long guns, but handguns are a no go.

You could try looking at a smaller shipper, as it’s not a matter of law.

You can send and receive a handgun thru an FFL dealer to an FFL dealer according to the 18-USC code (fed law) Let them worry about it..Its not that complicated..