The vortex viper 6.5-20 does not have a zero stop. It has spring loaded resettable capped turrets but that is it. However, mine has tracked very well and I have made 1 shot kills on over 25 big game animals ranging from 300-925 yards, dialing for elevation and windage for every shot. I have had it for nearly 4 years now, and not a single problem with it. MUCH better for hunting than a fixed 20x. If those two were my choices for hunting, without question I would go with the Vortex.While the SS has better glass the zero-stop and tracking are good features on the vortex viper the Vortex would be my pick mainly because I can dial back the magnification if the mirage is bad.
With all due respect, that's BS!At 72 my eyes are kind of worn out so 10x leaves me a little short.
BW