I have an SOB Tactical B sling. It has the qd attachment on my BCM rail and I have the rear looped through the stock with the slider buckles. No matter how tight I get that the sling tends to roll over the back of the stock and then it’s in the way when I bring the gun up and shoot. What am I missing? I set the sling up based on how Shrek suggests as well as other trainers.

Set up like in this link.

https://sobtactical.com/sob-b-sling-rifle-sling/