It's like doing a face to face transfer or show for possible sale
That's not covered in hrs, but people do it all the time
Yes, people do a lot of things all the time not specified in the firearm laws.
Why chance losing the right to own guns doing something for the sake of convenience?
Example: Coming home from a swap meet, you are hit by a drunken holiday party goer. HPD is called to the scene, and they find your cargo. There's not much chance at that time of night explaining it away as returning from the range, a gun shop, or the police station. Whether you are the unsuccessful seller or the lucky buyer, it won't matter. At least one, if not both of you, have broken the law (in my non-lawyerly opinion).
I meet at HPD or the range when viewing handguns for sale. Transfer happens at HPD. It avoids taking that risk.
Like I said, it's my personal feeling. People will do whatever they want, and they normally won't have a problem ... until they do.