Maybe an angled QD sling stud like one of these:

http://shop.talltimbertactical.stor...avy-duty-quick-detach-angular-attachment

But it looks like you have the Magpul with the QD swivel sewn into it.

TRIROCK Trircok QD Adapter Sling Stud and a GrovTec Push Button Base to Stud Adaptor would adapt it, but I don't know how sturdy it would be.