How to Time a Revolver

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To quote Larry Potterfield, the founder and chairman of the board of MidwayUSA, “If you shoot a revolver enough, it will go out of time.” This article describes fixing the timing on a Smith & Wesson revolver.

What is timing? Timing refers to when the cylinder locks in place when rotated. With proper timing, the cylinder will rotate enough that the cylinder locks in place before the gun fires. Timing is important because if it’s off, the chamber is misaligned, and this can result in poor accuracy and could be hazardous.

Timing for a Smith & Wesson is checked by cocking the hammer or squeezing the trigger very slowly to see if the cylinder is locked in place by the cylinder stop by the time the hammer is fully cocked in single action, and before the hammer falls in double action. If the cylinder does not lock in place when it should, the timing is off.

Some people recommend that light resistance be applied to the cylinder as it rotates while checking timing. Some guns will fail the timing test done this way even though they pass the test when no resistance is applied. Why does this happen? The cylinder ratchet (a.k.a. star) has a little side play, and this might be the cause. I see a lot of variation in how much wiggle room there is with the ratchets of my S&W revolvers.

How real-world relevant is testing timing with resistance? There generally isn’t any, or much, resistance to cylinder rotation when we’re shooting—it might depend on how dirty it is. So, opinions on applying resistance will be different depending on whom you ask. But in practical terms, proper timing with resistance might not be possible in every gun, depending on the tolerances.

Timing can be different in single-action and double-action modes. You might have good timing in single action but poor timing in double action. And the timing can be different for each chamber, so you need to check them all. Such was the story of the gun featured in this report. Early in its life, the timing was off on one chamber for single action and double action, and one chamber for double-action-only. With use, timing was off on all chambers, single and double action.

Replacing the Hand

The hand rotates the cylinder. It is attached to the trigger and fits in a window cut in the frame. It moves upward as the trigger moves to the rear. The hand’s nose fits in a half-moon cutout in the cylinder’s ejector ratchet (a.k.a. star). Each chamber has its own cutout, so timing could be different for each one.

As the gun loosens up a little with use and the parts wear, the hand doesn’t rotate the cylinder as far as it should. The fix is a new hand, specifically, an oversize hand. Oversize hands are wider, not necessarily longer. If you look carefully at the mechanism, it makes sense because at the last bit of upward hand movement, the hand normally slips off the ratchet. A wider hand means it will rotate the cylinder more before it slips off.

Jerry Kuhnhausen notes in The S&W Revolvers: A Shop Manual that the width of factory hands runs around 0.092 to 0.094 inch. Oversize hands run between 0.095 to 0.097–0.098 inch. Smith & Wesson makes oversize hands, and they are cataloged at MidwayUSA and Brownells. These could be a virtual drop-in fit. And if they correct the timing issue, you’re all set.

If you’re comfortable with disassembling your S&W revolver, you can do this yourself, though be warned that the tiny hand spring that applies tension to the hand is a tricky little devil, so make note of its normal position before removing the hand from the trigger because the spring usually comes out and you’ll need to reposition it correctly during reassembly. Also, because it’s so small, it can get lost very easily. You’ll need to reset the hand spring during reassembly, and this can be challenging. A vise and a punch make this easier. Hands are frame-size specific, e.g. K, L, and N Frame, so be sure to order the right one.

My S&W L-Frame Model 686-6 Plus seven-shot .357 Magnum revolver had a serious timing problem. After several thousand rounds, single- and double-action timing was off on all seven chambers with no resistance applied. I decided to fix it myself (if I could), and when I checked with MidwayUSA and Brownells they were out of S&W L-Frame factory oversize hands. Another brand they offered was Power Custom (the name has changed to Grand Masters, LLC). I ordered one.

The Power Custom oversize hand is not a drop-in component (though in some cases it might be). It is oversize in width and length. They say it should be fitted by a qualified, competent gunsmith who understands the mechanics of S&W actions. I’m just an amateur, but I wanted to give it a shot anyway.

The oversize hand must fit three things: 1) the window in the frame, 2) the cylinder ratchet, 3) individual chamber ratchet cuts. Correspondingly, metal must be removed from three places: 1) the window, to allow the hand to fit, 2) the hand’s nose, to fit the ratchet, 3) the ratchet, so the hand fits all the ratchet cuts the same. The last fitting (3) might or might not be required. It wasn’t required in my case.

Power Custom’s hand is wider than S&W oversize hands and indeed, it did not fit in the window of my gun. It measured 0.105 inch wide. My original hand measured 0.092 inch, on the small side of Kuhnhausen’s specifications. Fitting requires the window in the frame to be enlarged. I won’t go into those details here because they are in the instructions. Plus, I chose a different method for fitting the hand. I was not keen on the idea of widening the window, so I decided to make the hand thinner.

I did so by grinding the hand thinner with a fine India stone. It fit the window after removing 0.002 inch, and now it measures 0.103 inch wide. Next, the hand must be fitted to the cuts in the cylinder ratchet. This is what the hand pushes on to rotate the cylinder. Install the cylinder assembly. Mount the hand on the trigger and install this assembly in the frame.

Then fit the hand nose to the lowest ratchet. This is determined by squeezing the trigger and seeing which chamber ratchet cut has the smoothest fit (the least resistance). The hand’s full movement goes like this when you squeeze the trigger: It pushes on the ratchet to rotate the cylinder until it locks with the cylinder stop, and then it slips up and out of the way as the trigger moves all the way to the rear.

When I first tried this with the new hand, the cylinder would rotate and lock in place with the cylinder stop, but the trigger would stop before it moved all the way to the rear. The oversize hand’s nose was stuck in place, wedged between the window wall and the ratchet. This meant the nose needed to be thinned a little to slip up and out of the way.

I beveled the top inside edge of the hand with a small radius, as shown on the factory hand in the accompanying photograph. I didn’t want to remove too much metal here. I just wanted to break the edge. And I didn’t want to make it wider than the factory bevel. This aids the hand in slipping out of the ratchet cut in its final movement. Even with this bevel, the hand did not move all the way.

To provide further clearance for the hand, metal must be removed from the inside flat of the upper end of the hand’s nose (as per Power Custom’s instructions). The photo shows the small area on the middle side of the flat portion of the hand’s tip where to remove a little metal until the hand will move fully through its path and out of the way. It’s just the last few millimeters of the tip. (This is the inside surface of the nose flat, on the same side as the pins.) I removed only a little metal at a time and checked it for fit often.

With my gun, two ratchet cuts were a little lower than the others, and as I removed metal with a file and checked the nose for fit, the hand would start to move past the ratchet on those chambers, and the trigger would move fully to the rear, although I could feel resistance. On the remaining chambers, the hand would stop, and only after applying more force would it slip upward. This meant I was very close to the final fit.

I gradually removed a bit more metal until the hand would move all the way up on all chambers. There was a little resistance on some chambers, but it was very little. I stopped at this point and reinstalled all the remaining internals for a full function test and trigger feel.

As it would happen, along with moving all the parts under full spring pressure (rebound, hammer) while testing cocking and double-action pull, the slight resistance of the hand’s movement on the “tighter” chambers seemed to disappear. In light of that, I did not try to continue to fit the hand to the remaining chambers. It was done!

The timing was now good on all chambers. The cylinder locked in place before the hammer was fully cocked in single action and before the hammer dropped in double action. The final width of the nose tip was 0.099 inch, which is just wider than what Kuhnhausen reports for the widest width of an S&W factory oversize hand. A factory oversize hand might have fixed the timing, though it might have needed the largest size. As a final note, if I apply light resistance to rotation, the cylinder does not lock in place before fully cocked. Here’s where tolerances show up, and this gun’s ratchet has more than its fair share of side play. This model gun does not have ratchet alignment pins in the cylinder like older guns, and this might contribute to more side play.

Hand replacement can be a do-it-yourself project if you’re up to taking the revolver apart and studying how things fit and work. A drop-in part is ideal for this job, if it fixes timing. Hand-fitting the oversize Power Custom hand requires a more intimate understanding of the revolver’s operation.

My approach of thinning the hand to fit the window was a slight modification of Power Custom’s method, but it was the only deviation I made from their instructions. The task of reshaping the oversize hand is not for everyone. It requires you to have a good understanding of how the hand fits in the window and interacts with the cylinder ratchet, and you must have the patience to take your time fitting the parts. If there is any doubt in your mind, have a qualified gunsmith do it.

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