apparently there are several things to take a look at... rope stiffness & the way it's attached to the rings, & the kind of webbing being used, as well as the way it's threaded through the rings.
it's possible that some rings may have a smoother, slicker finish than others & maybe that would play some part. but i suspect the the rope & attachment and the webbing are the main things to look at.
some people have had no problems w/ slipping, but others have.
here is a picture of my rings being pulled uneven by the larks head.
http://www.hammockforums.net/gallery...5/P2250065.JPG
you can see the simple slip knot i used to stop it. even if i couldn't solve the slippage problem, using the slip knot (or what ever you call that) makes the rings the easiest adjustable system i've used yet. ...tim