What is a 2 point QD Sling? Besides being a favorite carry method for me, this is a type of sling that is designed to be attached using 2 points, one usually at the rear of the buttstock, and the other forward of the magazine well on the AR platform.  This allows the rifle to be slung across the body and held in a position that, with a little training, allows for rapid deployment of the rifle.  There are two swivels on either end of the sling, and they have a small push button in the end of the swivel that allows them to be released with the simple push of a button. The QD feature means that the sling can be rapidly connected or disconnected using quick-detach sling swivels and can be easily disconnected if you find yourself in need of dropping the sling for any reason.  

I prefer this style of carry because it allows the rifle to be held squarely in front of my body, not interfering with a pistol or any other tools that may be carried on the hip.  A quality sling will also have a quick adjust feature that will allow you to rapidly tighten or release tension on the sling with a quick tug of a built in loop in the sling.  This rapid adjustability can be incredibly useful if you are trying to get the rifle over an external plate carrier or want it a bit tighter to the body for hunting applications.  It also allows you to easily “swim” in and out of the sling as the situation may dictate.