@ 11:36 pm (GMT)
Todd FreeFound an outfit in Idaho, US, that make and sell backpack style slings. Picture of mine below. Where your rifle like a pack. Sooooooooo good.
I hunt with a 25L camelback pack and my rifle fits nicely on one side of the pack. I can get it to sit down the middle of my pack for the OCD part of me with a bit of messing around but it will shift to one side of the pack eventually.
No wobbling around, no bouncing as you walk, both hands free to get over rough and steep terrain, never shifts when bending over etc.
The straps come with Uncle Mikes swivels and the version I have has 1" quick release buckles if you are in a hurry to get it off without having to treat it like removing a pack. In four years I have never used the quick release buckles except for the first day I tried it. They work as described, quick.
The plastic buckles may worry some of you I suspect. I have not had a single issue with them in 4 years and I hike up to 10km every time I go hunting. I have had an Uncle Mikes swivel blow a pin once. Which was disappointing. It was the bottom swivel that went and magically I caught the straps before the rifle fell onto granite. At that time I did not carry an extra swivel, so I had to sling the rifle for the rest of the day and was not impressed. Will never go back to a single sling after using this one.
On the left strap I have used a marker and drew lines on the strap so I can quickly shorten it to the right length when using the strap on a bench or when standing or kneeling without resting the fore-end for quick short shots.
They only single drawback is that the butt of the rifle hangs down low enough that if I want to sit down and not remove the rifle, I need to sit on a log or something that will accommodate the butt of the rifles low position.
I cannot recommend these slings enough.
Timber Butte Outdoors - Outlaw QR Sling (web page is very 1996 but the product is very good)