3x9x40 = QR Low Rings.

I don't own an encore every one I know that does have fill screws in place of the iron sights, whether it was do fit or preference I can't say (sorry).

Have you considered the Warne Maxima Quick Detach Mounts? Reason askedI had a set of QRW's and wasn't impressed with their return to 0. I found they were inconsistant and thus went with the Warnes instead. They are consistantly within 1" interms of POI after removal and if requiredI wouldn't give them a momentsworry ifI had to remove when hunting (easily MOD). Great product, good service and strong mounts.

Maybe the QR's are better though.

Good luck.