A properly fitted Whelen style rifle sling has three functions
1. Carry the rifle.
2. Steady the rifle while aiming. Works best sitting, then prone, then offhand and with a hasty version of the Whelen sling.
3. Reduce felt recoil with a 1/3 forward and 2/3 backwards isometric hold.
Col. Whelen saw two problems soldiers had with shooting accurately.
One was needing maxiumum steadyness, and the other was fear of recoil.
His original design was shooting genious in action for improving steadyness and and reducing felt recoil.
Civilian hunters like Jack O'connor made subtle yet signifcant improvements which were more fitting to sport hunters.
I have a Whelen style sling on all my rifles that is fitted just for that rifle.
There are two verions, one a 1' wide military style two piece and a pure Whelen one piece 1" wide.
When in the sitting position I can keep near all my shots is a 3" circle at 300 yards.
To do this one must not have even a small pot belly. Getting into the curled sitting position to get your back bent over enough so your flats behind your elbow lay flat against your shins below is a must.
A belly gets in the way and pressure will be put on your lungs and mess with your breathing, Not good.
Also ones, back must be loose enough to curl over as shown in the photo
The front sling stud must be on the stock and the sling will hold the rifle in place against your shouder, but not tightly.
You pull it rearwards into your shoulder in with your right hand for right handed shooters and pull forwards with your left.
Your pull backwards should be about twice your push forwards. That creates the isometric tension which reduces felt recoil.
Since you need to push forwards against where the sling meets the swivel with your left hand, the swivel stud must be in the stock not more forwards on the barrel.
Again, well fitted and properly used, the Whelen sling really improves accuracy.
I have made a 2" x 8" peice of leather that goes right where my shoulder needs it to be for long carry comfort.
DB