Was getting frustrated trying to figure out how to carry a .22 rifle in my Tara when it dawned on me- biathlon double shoulder sling
I think it is possible to use the HPG shoulder harness for this by taking that larger middle webbing loop and connecting it to the front of a rifle on a swivel stud. If you remove the 2 shoulder strap webbing and you can thread and connect them through those dock and lock hardwear- then connect them to a swivel stud at the butt of the stock.
it could be worn over the Tara in theory, just disconnect the sternum strap and unmount it for your back- could make for a very stable way to carry
I was trying to get it to work but do not have any swivel studs on my rifles. I was cleaning my .22 so here is a mock photo with an old pea shooter
and here is the inspiration