To reduce the severity of cylinder turn lines I have for many years polished the contact surface of the cylinder stop. After removing the stop I lightly remove the tool marks from the top surface with a sweeping motion to maintain the radius and keep from introducing flat spots with 600 grit wet/dry placed on a piece of flat ground tool steel. When the tool marks are gone I go to 1200 grit to polish the surface and barely break the edge as viewed with a 10x magnifier. I then finish the polish using jewelers rouge applied to a piece of heavy leather glued to a hardwood block. Only moderate pressure is needed for any step in the process and no power tools to be too aggressive are needed. I was shown many years ago the proper way to close a cylinder to keep the stop in the cylinder locking slot during closing to eliminate the need to turn the cylinder to lockup. I'm sure turn lines are made more from improper closing of the cylinder than operating the action. Even properly tuned and timed revolvers will suffer a turn line from improper handling. Maybe this practice doesn't eliminate the turn line but it can't hurt. Any thoughts or input for reducing turn lines would be appreciated.
Cylinder stop polishing
- Thread starter Shoothog
- Start date
Register to hide this ad
bigggbbruce
Member
I would rather have a sharp edge for positive engagement.
bigggbbruce
Member
During armorers training, S&W advised we could break the edge on the high (frame) side of the ball of the stop when installing a new one. To quote the old (very old) manual...."the ball of the newly installed stop should always be stoned (referring to breaking the edge) and polished." I actually break this sharp leading edge with a ceramic stone, which removes any burrs and leaves a very smooth, almost invisible, polished crown.
On police issue weapons, I think the factory techs were more concerned about burrs on the stop at it's interface with the cylinder slot and the frame slot, and not so much about a turn line.
As we all know, turn lines are going to happen. As a matter of fact, the "turn line" on my old PPC gun became more like a "furrow" after several years and many 10's of thousands of rounds downrange. Not good on a collector's safe queen......but a badge of honor for a carry revolver IMHO.
On police issue weapons, I think the factory techs were more concerned about burrs on the stop at it's interface with the cylinder slot and the frame slot, and not so much about a turn line.
As we all know, turn lines are going to happen. As a matter of fact, the "turn line" on my old PPC gun became more like a "furrow" after several years and many 10's of thousands of rounds downrange. Not good on a collector's safe queen......but a badge of honor for a carry revolver IMHO.
Last edited:
Shoothog,
You're one of the few who intuitively recognize the issue and the benefits to correct it.
Two things are a given about the 'Cylinder stop track' or line:
1. The cyl stop is designed in such a way as to eventually leave a cyl ring half way between each pair of cyl lock notches. And any revolver can be fine tuned to mitigate making a cyl ring although with anything but conscientious handling it will usually develop anyway.
2. The cyl turns counter clockwise, and the left edge of the cyl stop is the leading edge which might appear to be the edge that causes the cyl ring. However there's more to this than may be immediately apparent.
As we know, the Smith cyl stop is centered in the frame and the upper surface is square (not slanted like a single action which uses an offset cyl bolt). Therefore the flat top surface of a DA cyl stop meets the cyl surface almost squarely. Almost because, considering the curvature of the cyl, technically only the center of the bolt's surface contacts the cyl. The top surface of the stop rubs against the cyl, not the left edge. That's why roughness or tool marks in the surface of the stop scribes the line. The left stop edge never has the opportunity to contact the cyl surface, certainly not by itself to cut into it.
So the leading left edge of the cyl stop does encounter the cyl notch approach ramp (notch lead) first. But the approach ramp is on an angle lower than the surface of the cyl, right? Therefore the left edge gets even farther from contact with the cyl as it enters the ramp. Then the center surface of the bolt loses contact as the right side half of the stop surface rides over the edge into the ramp until, at the beginning edge of the ramp, the right edge alone makes contact with the cyl.
That's when a sharp right side edge of the stop in contact by itself starts cutting at the entrance edge of the approach ramp and continues its cutting action all the way across the approach ramp, the stop continuing to rise as it gets deeper in the ramp until the right stop edge slips over, cutting the right notch edge as it goes, finally popping up into the notch.
Hence the importance of breaking the knife edges of the stop, but particularly the right side edge! Breaking the knife edge on the left edge of the stop is good too and helps prevent cutting, rounding or chipping of the left side edge of the cyl notch when the gun is cocked and the cyl begins to rotate.
A fine abrasive wheel in a Dremel tool, that I advocate only for removing tool marks in the surface of the stop, which can be pretty rough right from the factory, works very well in experienced hands and it's quicker; about 5 seconds. But never for breaking the sharp side edges. This is also the time to center the cyl stop in the notch and approach lead if needed. To center the stop, paint the cyl approach leads and the bottom of the cyl notches with a black Sharpie pen. Cycle the action several cyl rotations until you see the stop line in the black ink. If it's centered, your done. If not centered, reshape the curve slightly until the mark in the ink is centered. If there's no mark in the bottom of the notch, the cyl stop isn't fully engaging the notch.
Another 5 seconds with the cotton polishing buff wheel w/rouge will give a mirror finish to the stop surface and break the sharp side edges at the same time w/o ever focusing directly on the edges with any tool.
So I feel everyone is free to make their own choice of tool usage based on their own experience. If they feel more comfortable to do it with a stone and finishing off with 2000 grit paper, I don't say not to and I also say not to use a Dremel tool.
DA REVOLVER CYL CLOSING ETIQUETTE: even with perfectly timed actions, by design, the stop on DAs is raised early in the cylinder cycle. Eventually you will get a line on the cylinder but it should never be completely around the cylinder; only 1/2 way to the next cylinder notch. A simple habit when you close the cylinder, with your left hand grasp it 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. This will prevent scribing a full line 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 with notches in alignment with the cyl stop bolt 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. This WILL mitigate a full cylinder ring and at least limit it to an interrupted line.
You're one of the few who intuitively recognize the issue and the benefits to correct it.
Two things are a given about the 'Cylinder stop track' or line:
1. The cyl stop is designed in such a way as to eventually leave a cyl ring half way between each pair of cyl lock notches. And any revolver can be fine tuned to mitigate making a cyl ring although with anything but conscientious handling it will usually develop anyway.
2. The cyl turns counter clockwise, and the left edge of the cyl stop is the leading edge which might appear to be the edge that causes the cyl ring. However there's more to this than may be immediately apparent.
As we know, the Smith cyl stop is centered in the frame and the upper surface is square (not slanted like a single action which uses an offset cyl bolt). Therefore the flat top surface of a DA cyl stop meets the cyl surface almost squarely. Almost because, considering the curvature of the cyl, technically only the center of the bolt's surface contacts the cyl. The top surface of the stop rubs against the cyl, not the left edge. That's why roughness or tool marks in the surface of the stop scribes the line. The left stop edge never has the opportunity to contact the cyl surface, certainly not by itself to cut into it.
So the leading left edge of the cyl stop does encounter the cyl notch approach ramp (notch lead) first. But the approach ramp is on an angle lower than the surface of the cyl, right? Therefore the left edge gets even farther from contact with the cyl as it enters the ramp. Then the center surface of the bolt loses contact as the right side half of the stop surface rides over the edge into the ramp until, at the beginning edge of the ramp, the right edge alone makes contact with the cyl.
That's when a sharp right side edge of the stop in contact by itself starts cutting at the entrance edge of the approach ramp and continues its cutting action all the way across the approach ramp, the stop continuing to rise as it gets deeper in the ramp until the right stop edge slips over, cutting the right notch edge as it goes, finally popping up into the notch.
Hence the importance of breaking the knife edges of the stop, but particularly the right side edge! Breaking the knife edge on the left edge of the stop is good too and helps prevent cutting, rounding or chipping of the left side edge of the cyl notch when the gun is cocked and the cyl begins to rotate.
A fine abrasive wheel in a Dremel tool, that I advocate only for removing tool marks in the surface of the stop, which can be pretty rough right from the factory, works very well in experienced hands and it's quicker; about 5 seconds. But never for breaking the sharp side edges. This is also the time to center the cyl stop in the notch and approach lead if needed. To center the stop, paint the cyl approach leads and the bottom of the cyl notches with a black Sharpie pen. Cycle the action several cyl rotations until you see the stop line in the black ink. If it's centered, your done. If not centered, reshape the curve slightly until the mark in the ink is centered. If there's no mark in the bottom of the notch, the cyl stop isn't fully engaging the notch.
Another 5 seconds with the cotton polishing buff wheel w/rouge will give a mirror finish to the stop surface and break the sharp side edges at the same time w/o ever focusing directly on the edges with any tool.
So I feel everyone is free to make their own choice of tool usage based on their own experience. If they feel more comfortable to do it with a stone and finishing off with 2000 grit paper, I don't say not to and I also say not to use a Dremel tool.
DA REVOLVER CYL CLOSING ETIQUETTE: even with perfectly timed actions, by design, the stop on DAs is raised early in the cylinder cycle. Eventually you will get a line on the cylinder but it should never be completely around the cylinder; only 1/2 way to the next cylinder notch. A simple habit when you close the cylinder, with your left hand grasp it 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. This will prevent scribing a full line 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 with notches in alignment with the cyl stop bolt 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. This WILL mitigate a full cylinder ring and at least limit it to an interrupted line.
Perhaps this is redundant ( or I misunderstood), but the S&W cylinder stop is "flat" across the top, but the top surface is at a slight angle, approx. .008" higher on the frame side, leading edge of the ball, and lower on the plate side. Carefull polishing as you describe does no harm, but does little to mitigate the formation of the turn line. Very little attention to the ball of the stop itself is required, aside from observing the correct and unrestricted 4-way movement of the ball of the stop as it completes it's 4-way cycle down, up, forward and back in the frame window. (This necessary stop movement is dependant on proper fitting of the bevel to the trigger hook) Use care when polishing as advised in previous posts, as too much intervention here (ball itself).....i.e. removal of material.....can cause a host of issues including causing the stop not to hold properly.
The timing of the cylinder stop is determined by the interface of the bevel on the stop and the hook on the trigger. As these part surfaces wear, the stop will depart from it's "ideal" target of rising to impact the cylinder approx. halfway between the two notches, and will eventually come up sooner and sooner, making the turn line longer and longer. The wear will eventually create a flat on the top of the stop, and because of the wear to the bevel and/or trigger hook, cause the gun to malfunction, either by the stop not leaving the notch adequately, or the ball popping back up prior to the cylinder rotation beginning. Properly adjusted timing is at the heart of proper revolver operation.
The timing of the cylinder stop is determined by the interface of the bevel on the stop and the hook on the trigger. As these part surfaces wear, the stop will depart from it's "ideal" target of rising to impact the cylinder approx. halfway between the two notches, and will eventually come up sooner and sooner, making the turn line longer and longer. The wear will eventually create a flat on the top of the stop, and because of the wear to the bevel and/or trigger hook, cause the gun to malfunction, either by the stop not leaving the notch adequately, or the ball popping back up prior to the cylinder rotation beginning. Properly adjusted timing is at the heart of proper revolver operation.
Last edited:
Similar threads
