I used a Kifaru Universal Gun Bearer for years with my old Metcalf. I wasn’t wild about it but never tried anything else. When packing meat though while I still had my rifle on me, I’d tuck the butt of my rifle into the elastic pocket on the side of the pack and strap it under the scope using the side cinches. Worked okay unless the pack was a really wonky shape because of the meat. Then I’d just put the rifle back into the Gun Bearer and deal with it for that initial pack out.
I think that Exo sling could probably be used on a Metcalf.