If the drag line extends more than halfway between the cyl locking notches, it's from user handling; turning the cyl after the cyl bolt pops up as jstanfield correctly pointed out above. A drag line that's only halfway between the locking notches is normal. New Model Rugers and S&Ws are designed this way to insure reliable lock up under rapid firing.
As "Chuck 100 yd" posted, I also simply polish the bolt on all revolvers when I first get them. Takes one minute with a Dremel tool and goes a long way towards mitigating the ring. After that, I never think about the ring again.
If the ring really bothers you, there's a cyl bolt plunger (in the hammer) modification that will eliminate the ring on new models from normal cocking. However, recognize w/o conscientious handling of new models, modified guns can still cause a ring.
Even if the hammer plunger is modified you can cause a ring if you lower the hammer w/o cocking all the way back 1st (a SA no-no!) or when you close the loading gate w/o a cyl notch being directly above the cyl bolt; as soon as you cock the hammer or turn the cyl into place to lock it, you scribe a ring just like on an old model.
For DAs a simple habit when you close the cylinder, will prevent a full cylinder ring and at least limit it to an interrupted ring. With your left hand grasp the cyl around the bottom of the frame with thumb and forefinger in opposing flutes positioning them at 3 and 9 o'clock when closing the cylinder will prevent scribing and becomes so natural after a while, one doesn't even have to think about. This works on five shot cylinders as well by positioning two flutes at 4 and 8 o'clock. Once closing the cylinder in alignment becomes a habit which is like after the 2nd time you do it for most of us, it's no "effort" what so ever; or about as much effort as remembering to breath.
