I briefly used Warne ultra high Maxima 1" QD rings on an AR. The scope I was using worked out ok without needing cantilever mounting. That set of rings was noticeably lighter than the subsequent ADM mount I used later. I liked them quite a bit, though they were demos and the previous user stripped some screw holes.
I also have a Leupold Mk2 cantilever 1" mount that seems fairly light, I'm guessing its one of the lighter 1piece AR mounts out there. Kinda wished I had weighed all the mounts and rings while they were off, just for the heck of it..