For what it's worth, I use hasty in standing with my AR-15, loop in all other positions.
Mine is set up with a standard M1 GI cotton sling, swivels on the gas block and (fixed) A2 stock. I've tried just about every sling and method there is over the years and this simply works best for me.
Ask me about Appleseed! Send a PM or see me in the Appleseed subforum.