I tried them in my RPR with H1000 and the best groups were in the 7's. My load with 285 grain ELD-Ms pretty well stays in the 5's.
I chose to maintain magazine length so they might have been awesome single feeding closer to the lands. Magazine length puts me at around 0.140" jump. The 285 ELD-Ms jump around 0.080" at magazine length.
I did manage to get ahold of some Retumbo and N570. I had a box of 300 grain A-Tips left over so I loaded OCW rounds for both but haven't shot them yet. I figured I might as well find out.