My favorite AR-15 3 gun stock is the Magpul PRS because it’s adjustable. I can have it fit me close to perfectly. The downsides are that it is heavy and I don’t like the sling attachment setup the way it comes from Magpul. Every once in a while during a 3 gun match its necessary to use a sling. I like QD (Quick Detach) sling mounts because they are fast, reliable, and are flush fitting. There is now a product that will allow conversion of the Magpul PRS sling system to QD.
The MGSS PRS QD Adapter will mount anywhere on the PRS stock that you already have a web sling attachment. I chose to mount mine in the rear because I like to use a 2 point Viking Tactics quick adjust sling. The QD mount is machined steel and has a built-in rotation limiter to prevent the sling from twisting up. 
The MGSS PRS QD Adapter is a great idea and a well executed product. It should have come on the stock from Magpul. The only downside is that it is relatively expensive at $34.99.
The Brownells Item # is: 41516