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07-23-2017, 02:14 PM
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End Shake and Carry-up Questions
Hi All,
I have a 686-4 and am wondering if what I'm encountering is within normal spec:
1. Carry-up: When slowly cocking the hammer single action, on all six chambers the cylinder stop drops in the notch before reaching fully cocked. All seems fine there. However, when slowly pulling the trigger double action, on four chambers the cylinder stop drops before the hammer drops (good) but on two chambers the cylinder stop drops right as the hammer drops. Since those two are different (slower) than the other four, would you guys say there is an issue that needs addressing? It is not shaving lead, nor are there any other visible signs of issues.
2. End Shake: With all chambers completely empty and trigger held all the way back with hammer all the way forward, there is a slight detectable forward-backward movement of cylinder. Not a lot, just enough to feel with fingers. I do not have feeler gauges to be more precise. Now, with either spent casings or snap caps in chambers, under the same test it is tight as can be. No detectable movement by feel. Do you think this is good to go?
Thanks for any input!
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07-23-2017, 03:03 PM
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Carry Up and End Shake
Check carry up in single action only. Take the hammer with your thumb and pull back slowly. Go as far back as you have to to see if the cylinder stop will go from one notch to another. This should happen in all six cylinder notches. Also, check with six empty shells to see if it carries up. If it carries us with shells, you should leave it alone. If it doesn't carry up, this means the cylinder is not lining up with the barrel. To check end shake, first measure the Barrel to cylinder (B/C) gap. The normal usable range is .004" - .010" with .006" being ideal. Then hold the cylinder forward and insert the thickest gap gauge that will fit between the cylinder face and the rear of the barrel with minimal friction. Subtract this measurement from the BC gap. This will be the cylinder endshake. Anything over .002" is considered excessive. Hope this helps.
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07-23-2017, 06:23 PM
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Quote:
Originally Posted by OldChief
Check carry up in single action only. Take the hammer with your thumb and pull back slowly. Go as far back as you have to to see if the cylinder stop will go from one notch to another. This should happen in all six cylinder notches. Also, check with six empty shells to see if it carries up. If it carries us with shells, you should leave it alone. If it doesn't carry up, this means the cylinder is not lining up with the barrel. To check end shake, first measure the Barrel to cylinder (B/C) gap. The normal usable range is .004" - .010" with .006" being ideal. Then hold the cylinder forward and insert the thickest gap gauge that will fit between the cylinder face and the rear of the barrel with minimal friction. Subtract this measurement from the BC gap. This will be the cylinder endshake. Anything over .002" is considered excessive. Hope this helps.
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Thanks for your response. Checking carry-up in single action, the gun seems fine -- the cylinder stop drops in all six notches before the hammer is fully back/cocked. Are you saying that it doesn't matter what it is doing in double action as long as it passes this test in single action?
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07-23-2017, 06:57 PM
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Smith & Wesson double action triggers are meant to be pulled through in a single, fluid and fairly swift motion. The rotational inertia from the cylinders mass carries it to a stop at the bolt.
Many S&W revolvers function quite well with a slow double action pull with the bolt locking into the cylinder notch well before the hammer reaches its apex. My 642's, a 67-6 and 617-6, all post 2008 guns, lock very early allowing "staging" the trigger. Many of my older Smiths do not lock that early in D/A firing and are not easy to "stage". Fired at normal D/A speed the lock up is just fine, and single action, all are, of course, perfect.
The most worn of my Smiths, a 1947 Military and Police K frame .38 Special has excellent timing and carry-up when shot single action. Double action is good when I shoot with a quick, straight through pull. Pull the trigger slowly and the cylinder will occasionally not rotate far enough to catch the bolt. I'm sure a new hand, bolt and possibly ratchet Star could make the old K frame "stage" like my 67-6, but why bother? It's still working as designed.
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Last edited by steamloco76; 07-23-2017 at 06:58 PM.
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07-23-2017, 07:14 PM
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To speed up slow cylinders you take a small punch and hammer, open the cylinder, support the front of it on the edge of a table, put the punch on the slow part of the star, give it some firm whacks, works like a charm, no guts, no glory.
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07-24-2017, 01:41 AM
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My newer Smiths seem to lock-up in double action earlier than my guns made in the 70s. As mentioned above though, the old guns are fine if you pull the trigger straight through in a single motion (it doesn't even have to be fast - just firm and straight through). I hate it though if I have a new shooter shoot one of them - they pull the trigger agonizingly slow and wonder why the gun spit lead back at them. I gringe!
BTW, the new Kimber K6s locks up super early and makes staging to what amounts to single action easy. It's nice, but that just isn't how the old S&W revolvers were timed.
Last edited by Ashlander; 07-24-2017 at 01:43 AM.
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07-24-2017, 09:27 AM
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Thanks for all the responses. It sounds like the carry-up on this gun is okay.
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07-24-2017, 12:39 PM
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As earlier noted, carry-up should be checked with empties or snap caps in place as they affect positioning of the extractor star and give a truer diagnosis of carry up.
Check carry up in both single and double action. Despite what some report, inertia should not be a trusted replacement for a properly timed rotation; the revolver should carry up properly in slow double and single action pull, if it doesn't, it does not carry up.
You report acceptable carry up; on the charge holes that align in time with the hammer dropping, you're getting close to either needing a new hand or ratchet adjustment. Do not hammer the ratchets yourself to "fix" them -- they're one of the most difficult jobs for a good revolversmith to do right, and most everyone else will just make a bigger mess than they started with.
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