I am upping this because I loved the concept and followed through. I owe this thread pictures!
Searching for this topic yields few, few results. But add the keyword "hangar" and it is all too clear! but this thread is by far the best google result.
Anyways, I took a piece of 1/2" delrin and cut it to the width of my shelf standard. I flatted the ends 7/16" so they would sit flat on the shelf standard brackets. I then turned down four grooves to .37" to cradle the handi barrel pivot points and do not slide sideways.
In 8.5" of width I have 4 handi barrels hanging barrel down, with the barrels in the notches of my existing safe shelf. They are stored high and out of the way and I can access any of them without moving other rifles It frees the shelf bottom to hold my frame. (And two forends and a second stock and anything else I buy in the future for my handi!) The total cost of all this was zero, as the only materials used was a piece of delrin and two bolts.
I am upping this thread to remind other folks its here, to laud the brilliance, and to (later tonight) share my homemade iteration.
Thanks yet again, graybeard outdoors.