Smith and Wesson double-action revolvers develop a drag mark on the cylinder soon after acquisition. Some mistakenly believe it is a sign that the gun needs adjusting. Some believe it can be corrected to avoid the ring but "live with it".

The cylinder stop (Colt calls it a bolt) drops down and away from the cylinder for a part of the cylinder's unlock followed by rotation for a portion of the advance to the next locked position, then springs back and rubs the cylinder, continuing to drag until it engages the next slot.

I recently acquired a 1970 model 15-3 that has indicators of having been fired very little, one being a barely discernible ring when I got it. Since then, the ring is more observable and complete, slot-to-slot, just from a short time on the range and from handling and dry firing.

Observing the timing, there should be a shorter drag mark and an area unmarked where the stop does not contact the cylinder during that port of the rotation. So what is lengthening the drag ring where no contact appears?

It occurs each time the cylinder is unlatched and closed and the cylinder turned to a locked position. The stop never lowers during latching/unlatching and manual indexing.

The drag ring is a trade-off for a timing mechanism that is very positive. Colt's double-action revolvers have mechanisms and timing that does not drag the bolt like S&W does. But when the Colt goes out of time, it can be very difficult to adjust.

Enjoy the ring.