Howdy
That is a pretty good explanation.
With most single action revolvers, when properly timed, the bolt will pop up when the lead in to the cylinder locking notch is directly over the bolt. This Colt of mine is properly timed. Notice the 'skid mark' left behind by the bolt popping up in the lead in to the cylinder notch. The skid mark is dead center in the lead in. Note: Please excuse the dark rust spots on the cylinder, that's how it was when I got it. But at least it was properly timed, and nobody had abused it creating a drag mark around the cylinder. On a Colt style lockwork, if the hammer is lowered from the half cock postition, the bolt remains up, pressing against the cylinder, and if repeated enough times, when the cylinder is rotated the bolt will put a wear mark on the cylinder.
Here is an Uberti Cattleman of mine. It is a little bit out of time, notice the 'skid mark' starts just before the lead in. The bolt is rising a little bit early on this gun. I don't shoot it much, so I have never bothered to have the timing adjusted.
Rugers are different. They are purposely designed so that the bolt rises earl, rubbing directly on the cylinder. That is part of the design. It is possible for a gunsmith to alter the timing, but right out of the box, that's what Rugers do. Here is a New Vaquero, with a typical rub line starting about halfway between the chambers. Again, that is normal, that is the way the engineers at Ruger designed it.
Now, a properly timed Three Screw Ruger is a different story. When properly timed, it should be just like a Colt. The bolt should pop up in the lead in, just like a Colt, and not leave a ring on the cylinder. If there is a rub mark, somebody was probably lowering the hammer from half cock, allowing the bolt to remain pressed up against the cylinder.
Double Action revolvers are a different story. With the hammer down, the bolt is up. When you open the crane to load or unload, the bolt is still up. When you close the gun up again, the bolt is still up. Unless you are very careful to align the cylinder so that the bolt pops into the locking notch when the cylinder is closed, a ring will develop. That is just the way it is with Double Action revolvers. I own a zillion of them, mostly Smiths. Most of them I have bought used. I do not consider a ring around the cylinder a sign of misuse in a Double Action revolver, I consider it to be normal wear and tear, just like a little bit of holster wear.