Just saw this on the NFA Review channel. Pretty neat. Large external knob that pushes a smooth pin (where there's usually a set screw adjustment). Surprisingly inexpensive ($200 msrp) for a new, probably low volume item. I've only seen a few toolless designs for a DI gun but they seem rare.
RIFLESPEED Gas Controls for AR15 and AR10 Style Rifles
www.riflespeed.com