I use both the Leupold and Warne QD rings. Both work well, have never had any issues with them loosening. Return to zero is always acceptable, but I ALWAYS verify at the range.

It may be worth mentioning in case some are not aware, Leupold makes two systems. A QR base and ring system and they also make a QD ring. The QR system is a stand alone Leupold ring and base system. The QD rings are Weavers style base compatable.