How to check the timing?

[corgiS&W]

I have a M66 that I was showing to a LGS owner/smith. He pulled the hammer back while letting his finger drag on the cylinder, and then removed his thumb from the hammer. He repeated this 6 times and then told me that all 6 chambers were out of time. It would not be a problem when shooting SA, but DA may leave some lead on the forcing cone; he looked carefully, but did nt see any. What was he hearing, feeling, or seeing when he was doing this exercise?

I think I've heard or read that timing requires work on the "hand". How bad does it have to be to require this work? When I first bought the revolver several years ago [used, it's a no dash], there was a slight roughness in the trigger and I took it to a well-thought-of smith in another part of town. He fixed the trigger but made no mention of the timing. Wouldn't that be something a quality smith would have checked? Or only if I had asked? TIA.

 

[ken158]

Slowly pull back the hammer and watch for the cylinder stop to lock into the cylinder notches prior to the hammer locking back in single action. Have empty cases in the cylinder to increase weight simulating a loaded gun. If the hammer is locked back and the stop is not in the notch, then your timing may be off. But, don't do this slowly - but as you would do in firing the gun in single action. The idea is to have the cylinder locked prior to a round going off. In general, a wider hand will lock up earlier but may require a ratchet adjustment which is not for a novice.

 

[TucsonMTB]

Let me guess . . . was this gentleman hoping to buy your revolver? On more than one occasion, I have seen comments here on the forum describing the finger drag test as a scam to convince a seller their healthy revolver has a problem.

As Mr. ken158 described, it is only important that the action lock properly at normal cylinder movement speeds.

 

[Neumann]

It is not a scam to devalue a revolver. The cylinder should lock on all six chambers if you apply a little drag on the cylinder as you cock slowly. The same should happen if you pull the trigger DA. I have one revolver that fails that test - a Colt I bought 40 years ago and shot the heck out of it. I pass on revolvers that fail that test. I might make an exception for something really hard to get, but I haven't graduated to the "collecting" stage yet.

Failure doesn't necessarily mean you can't shoot it. If the cylinder is clean an lubricated so that it spins freely, a S&W operated by staging the trigger will spin and lock up by inertia. IMO that's a bad practice to establish, since it is more suited to the target range than for self defense.

Problems could be the hand, but more likely the star is worn or not keyed tightly to the cylinder, or the crane could be out of alignment or have excessive head space.

 

[Watchdog]

I've seen an LGS guy do this finger drag "test" on several occasions.

I personally think it's a bunch of hooey.

 

[John R]

I've seen an LGS guy do this finger drag "test" on several occasions.

I personally think it's a bunch of hooey.

It's something sticky all right, but not sure it's honey.

 

[Watchdog]

It's something sticky all right, but not sure it's honey.

"Hooey" and "Honey" are two different things.

Honey is a natural substance produced by bees. It's quite tasty on and in lots of things.

Hooey is...well, let's just say hooey is a euphemism for the natural byproduct of male bovines.

 

[corgiS&W]

Nero Wolfe might call it flummery.

 

[Nightowl]

Many folks believe that if the cylinder stop engages the cylinder notches at operating speed that the gun "carrys up" or times properly. I want all my guns to time when I very slowly cock the hammer and the cylinder stop engages before full cock, consistently on all chambers. I do this with chambers empty, because I have really never found any difference when putting empties in the cylinder. If it times like this, it will time just as well with a little pressure retarding the cylinder rotation. That will not really stop the rotation of the cylinder before lockup, unless the cylinder is out of time. If timed properly, the cylinder will rotate to full lockup with and without pressure on the cylinder. Some folks might think I am too picky about this, but almost all the old guns from after the war until the late 60s will time this way, if they have not been worn down too much.

 

[usnrigger]

I agree, i check to make sure all chambers "Carry Up" fully by slowly pulling the hammer back. the cylinder stop should engage the cylinder notch before the hammer gets fully cocked. I dont apply any pressure to cylinder, and i dont put any dummys in the cylinder. Some do add dummys and i can see this would add mass to the rotation. I just worked on a Pre K22 (1948) that when i inspected it 2 chambers did not fully come up, I also had "Yoke Shake", as well as "End Shake". I gave it a full tear down and deep clean, make sure to pull the locking bolt and clean that out. Just by giving it a good scrub and oil i checked the Carry up, and "snap" all 6 carried up perfect. I swapped the side plate screws and yoke shake corrected. These always seem to get swapped around sometime in life. I stretched the yoke out to correct the End Shake and checked cylinder gap(.008"), yoke alignment and heaspace.

alot of things can come into play with carry up, many times a good clean and oil can fix it, other things like correcting yoke alignment, bent extractor rod, or checking fit on locking bolt. dont always go straight for the hand.

When i look at a revolver to buy i do check as much as i can at the LGS or Show. Carry Up, End Shake, Yoke Shake, Cylinder Gap, Extractor Rod running true, as well as the normal fuction stuff. Yes if i see some of these things need correcting i always adjust the price im willing to give. Its more work for me to fix and for some to pay to have corrected. The two hardest things to get fitted properly is having to refit the yoke screw to the yoke button or properly fitting a locking bolt, id rather not find out after i buy it i may have to do one or both of these, its very time consuming.

Saying carry up is not a big deal is like saying my V-6 runs, but 2 cylinders are missing out. Yeah its working but not properly or the way it should.

USNRigger

 

[corgiS&W]

This morning I tried a different test. I pulled the trigger slowly in DA [I think this is called staging] and for all 6 chambers I heard the cylinder stop snap into the cylinder before the hammer fell. And in each instance the cylinder was locked in place. This would seem to indicate that the cylinder is in-time. However, when I pull the hammer back slowly in SA, there is one chamber where I do not hear the stud click into place until the hammer is fully cocked. I will do a thorough cleaning of the star today to see if that has any effect on this. I can't see any logical reason why the SA staging should be any different from the DA staging, particularly since the hammer is further back in SA. I'll also check to see if there is any dirt or a burr in the cylinder notch.

Be back later...

I cleaned the ratchet with cleaner & a brush and deburred the cylinder notches with 600 SiC paper. Took it to the range and fired with no problems in either SA or DA. I asked the on-site gunsmith to look at the timing. He handed it back and said I'm not shooting it enough. I think I'll let the issue rest now.

 

[cgt4570]

Sometimes it's as simple as a little burr on the ratchet tooth. Otherwise, it's time for a new hand or some careful peening of the low spot on the ratchet.

 

[corgiS&W]

Sometimes it's as simple as a little burr on the ratchet tooth. Otherwise, it's time for a new hand or some careful peening of the low spot on the ratchet.

I think it is the ratchet tooth, but why the different behavior between cocking the hammer and staging the trigger? Is the hand engaged differently? I never see the failure to lock when the hammer is pulled all the way back in SA, only when it is pulled back very slowly.

How would you go about peening the ratchet tooth? I think I know which tooth is problematic, but I should put it under a scope to get a good look. Wouldn't it be easier to replace the ratchet than the hand?

 

[PA Guns & Ammo]

Every time I check a revolver for purchase, I check to see if the cylinder stop engages when I slowly cock the hammer. Sometimes it will not unless you pull the hammer back a little faster. I just assume it was dirty and needed to be cleaned and lubed.

James

 

[John R]

"Hooey" and "Honey" are two different things.

Honey is a natural substance produced by bees. It's quite tasty on and in lots of things.

Hooey is...well, let's just say hooey is a euphemism for the natural byproduct of male bovines.

Sorry, old eyes I guess.

 

[RichCapeCod]

I'm not a pistol smith but was shown how to check the timing on a revolver by an NYPD smith many years ago. He suggested insertion of spent cases in the chambers when this is done. To check the "carry up" (term he used) he would manipulate the action in both single and double mode. He also used a range rod (a metal rod the exact diameter of the bore). With each rotation of the cylinder to the next chamber he'd run the range rod into the chamber from the muzzle end. If it "ticked" (the rod hit the edge of the chamber as it entered) then there was a timing issue.

I do recall he put a bit of (not an excessive amount) of finger pressure on the outside of the cylinder when he was manipulating the action.

I also noted that at the end of the "test" the smith would cock the revolver and push on the hammer's spur to test for "push-off." If the hammer did not remain in place (if it flew forward) with moderate pressure (no idea how to describe what that means) then the handgun needed repair.

Hope this helps.

Rich

Forgot to add; he was not too "gentle" when working the action during this procedure.

 

[usnrigger]

Would strongly suggest that before you jump right to hand or ratchet correction that that you: Clean and oil pistol completely(not just areas) this includes the pulling and cleaning locking bolt. Yoke alignment, end shake, yoke shake. ejector rod running true, locking bolt fit correctly. all of these could have a factor in "Carry Up".