Well, I need to retract part.of my original statement...
I went back and stared at the rings that had frustrated me, because it really was baffling (I had ID's them as Leupolds, couldn't figure out why they would sell them...)
Turns out that the clamping plate is slightly different top to bottom, so I tried them reversed and they did, just, get a bite on the Marlin rail.
I also re-reversed them and tried them on an 11mm CZ 455 rail where they got what I would call a solid bite.
So, they are staying on the CZ and I owe Leupold an apology.
Still looking for nice, LOW, blued steel rings for the Marlin 81, hopefully without some giant thumbscrew sticking out the side. Keep the recommendations coming. I'm going to search more tonight.
