I currently use Ahrends Tactical Smooth grips on my 686 round butt. I like it a lot (in fact I use Ahrends Tactical Smooth for all my K/L frames).
But, today at a gun show, I handled a new 586 Classic and it had what seemed like an old "Coke bottle" style-like grips and they felt SUPERB! They were fitted perfectly with nice smooth, rounded edges.
I was a bit surprised because I heard that they might be made by Altamont, and I was not impressed by one set of Altamont K round conversion target I bought before (good fit and trim, but the upper back strap grip area is very flat and sharp, almost 90 degree angle, instead of being nicely rounded, and is very uncomfortable when gripped hard).