Duece, are you doing a Magpul QD?
I was running a Strike Industries qd/hook combo that fits inside the pic rail. Which allowed my BUIS to fold over it.
The Strike industries is nice, but takes up a bit mor real estate that i would have preferred.
There is another company, that makes a QD mount for pic rail, that sits flush with the pic. This product looks kinda like a "T" and takes up only one slot. This is on my list to try. Nice a low pro, with a tiny footprint.