cylinder hard to turn

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DaTerminat'r

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I bought a model 31-1 with 32 S&W Long recently in excellent condition. The cylinder doesn't rotate smoothly on 4 of the holes. It gets tighter on these 4 holes. It's not very tight, but enough that I can't spin the cylinder like I can on my other revolvers. When I spin the cylinder with it opened, the extractor rod and the back of the center pin wobbles a tiny bit, hardly noticeable to my eyes. I took the extractor rod and the center pin out, and put them on my hand drill to spin it. Again, they seem to be straight to my eyes. How much of a wobble would cause cylinder to bind? What should I do? There isn't any revolver gunsmith around here.
 
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Clean under the extractor star. Get solvent in there, scrub the cylinder and the underside of the extractor with a tooth brush, then wipe it all out. See if your problem goes away.
 
I would look for other issues first before condeming the ER especially since you said it gets worse the more you shoot and parts expand and residue builds up.

You have classic symptoms of a cylinder binding on the throat of the barrel at the gap or on the recoild shield. Do you experience the problem with and w/o empty chambers? After shooting the gun but before cleaning it, and in good light with a magnifying glass if you have one, look for rub marks on the front face of the cylinder and on the recoil shield. If so, these are very minor issues.

If there is evidence of rubbing on the cylinder face, hone the end of the barrel where it aligns with the rub marks. If on the recoil shield and it looks like brass rubbing, hone the recoild shield (this is not the problem if there is binding with empty chambers). If the rubbing is in the little depression where the extractor star nests, look for burrs on the surface of the star and carefully hone them and any machining marks on the surface smooth.
 
Dragon88 said:
Clean under the extractor star. Get solvent in there, scrub the cylinder and the underside of the extractor with a tooth brush, then wipe it all out. See if your problem goes away.
Click to expand...

Excellent advice. Also the rear edges of the barrel might need scrubing of any lead residue.
 
I didn't explain the problem very well in post #1. I didn't mean that the cylinder gets tighter as I shoot at the range. Instead, the first bullet at the range is same tightness as the 100th bullet at the range on the same day, before cleaning. So, dirt or leading is not the culprit. Also, when I say tight, I meant there is slight amount of drag when I pull the hammer back slightly and rotate the cylinder by hand. On my other revolvers, when I do this, I can get the cylinder to spin. But the M31 would not spin.

I can see .004 clearance at the cylinder gap at all times. And there's nothing in the front of the cylinder that I can see is binding.

On the recoil shield, I don't see any marks that indicate rubbing by the extractor star.

It's definitely not the cylinder gap or recoil shield or dirty extract star.
 
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Did you actually scrub out the area under the extractor star as I suggested? Are are you just assuming it's clean? Round count at the range is irrelevant if there's old, built up crud in there.
 
Yes, I scrubbed it with a brush and hoppes9. And under the star is brand new clean. The gun is "new-in-the-box" when I bought it. And I put about 200 rounds thru it. When I first got the gun, I notice the cylinder was a bit tight. I thought that was normal for a brand new gun. I thought shooting it would loosen it up. But it's not, and it might be getting tighter.
 
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Try removing the cylinder and yoke, separating them, and cleaning them thoroughly. Pay particular attention to the barrel of the yoke, the central bore of the cylinder, and make sure they're clean & oiled at reassembly.
HTH

Larry
 
Ok, so cleanliness has been eliminated. And it's a new gun. It rotates freely when open but tight when closed, right?

Time to become a detective by process of elimination:

Open the cylinder and push the thumb piece (cylinder release button) to the rear and hold it there. Now cock the hammer and also fire it in double action. If no tightness doing those, proceed to next step.

Take eject rod and long skinny Center Pin (locking pin) out, close cylinder and while holding it closed and thumbpiece to the back again, operate hammer in double and single action. Then also, with right thumb holding hammer far enough back to drop cylinder stop in bottom of frame, hold thumbpiece back with left thumb and turn cylinder by hand counterclock-wise. Is tightness still there? If not, proceed to next step.

Observe the outside surface of the ejector rod for rubbing on only one side where it turns inside the yoke hole. Remove the front sideplate screw. With gun laying on it's right side, barrel to the right, hold cylinder in left hand and with right hand pull the yoke from the gun and from the cylinder at the same time.

Observe the rotating surfaces on the yoke shaft, look for turn marks on only one side, look for machine marks and burrs. Look for rub marks and burrs on the front of the cylinder center hole.

Report back.
 
See my comments below in red.

Hondo44 said:
Ok, so cleanliness has been eliminated. And it's a new gun. It rotates freely when open but tight when closed, right? Yes.

Open the cylinder and push the thumb piece (cylinder release button) to the rear and hold it there. Now cock the hammer and also fire it in double action. If no tightness doing those, proceed to next step. Yes, no tightness.

Take eject rod and long skinny Center Pin (locking pin) out, close cylinder and while holding it closed and thumbpiece to the back again, operate hammer in double and single action. Then also, with right thumb holding hammer far enough back to drop cylinder stop in bottom of frame, hold thumbpiece back with left thumb and turn cylinder by hand counterclock-wise. Is tightness still there? No, no tightness.

Observe the outside surface of the ejector rod for rubbing on only one side where it turns inside the yoke hole. Yes, I see very signifcant rub markings on the inside of the yoke, where extractor rod turns.

Remove the front sideplate screw. With gun laying on it's right side, barrel to the right, hold cylinder in left hand and with right hand pull the yoke from the gun and from the cylinder at the same time. I can't pull the yoke out. Looks like the extractor rod is putting pressure on the yoke.

Observe the rotating surfaces on the yoke shaft, look for turn marks on only one side, look for machine marks and burrs. Look for rub marks and burrs on the front of the cylinder center hole.

Report back.
Click to expand...
 
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I put a credit card between the front of the extractor rod and the locking bolt. With the credit card, there's no more tightness spinning the cylinder. I pulled the credit card off, and the tightness came back.
 
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Bingo! Now we're really pinning it down. With the cylinder closed, looking at the front of the frame, is the yoke joint tightly closed or is there a slight gap?

If there's a gap, the yoke may be slightly sprung. If no gap, the ejector rod has to be the issue in some way. Look in the end of the knurled (checkered) end of the ejector rod. Does the hole look round or is one edge of the hole deformed or burred over? If the hole looks good, that ejector rod is not straight and inspect the little locking bolt under the barrel for burrs. Open the cylinder and while holding the gun muzzle down and looking at the end of the ER, give the cylinder a good spin. Look for runout (wobble). Hold the gun with muzzle to the left and slightly down, give the cylinder a spin and observe the end of the ER from the side and look for wobble.

By the way, what barrel length do you have? What year was the revolver new or what's the serial number?
 
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These are my favorite S&W revolvers. Here's one of my favorites, a 31-1 from c. 1967 with added target sights, trigger, hammer and grips:
orig.jpg


orig.jpg


orig.jpg
 
See red comments.

Hondo44 said:
Bingo! Now we're really pinning it down. With the cylinder closed, looking at the front of the frame, is the yoke joint tightly closed or is there a slight gap? Yes, it's tightly closed.

If there's a gap, the yoke may be slightly sprung. If no gap, the ejector rod has to be the issue in some way. Look in the end of the knurled (checkered) end of the ejector rod. Does the hole look round or is one edge of the hole deformed or burred over? Looks pretty round. If the hole looks good, that ejector rod is not straight and inspect the little locking bolt under the barrel for burrs. Locking bolt looks good. Open the cylinder and while holding the gun muzzle down and looking at the end of the ER, give the cylinder a good spin. Look for runout (wobble). Hold the gun with muzzle to the left and slightly down, give the cylinder a spin and observe the end of the ER from the side and look for wobble. I don't see much wobble. My other revolver has much more wobble.

By the way, what barrel length do you have? What year was the revolver new or what's the serial number?
Click to expand...

The ER looks straight. I'm thinking about filing down the locking bolt a little. Or enlarge the hole on the end of the ER. Because the cylinder is slightly tight all the way around.

I have a 31-1 3" barrel fixed sight from 1981. I'd love to have a gun like yours Hondo.
 
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DaTerminat'r said:
See red comments.
The ER looks straight. I'm thinking about filing down the locking bolt a little. Or enlarge the hole on the end of the ER. Because the cylinder is slightly tight all the way around.

I have a 31-1 3" barrel fixed sight from 1981. I'd love to have a gun like yours Hondo.
Click to expand...

That's good news! Removing the locking bolt pin is tricky. It takes a pin punch with a cupped end and it's easy to ding up the bluing around the pin. I have a procedure to follow if you want to try that.

With the cylinder closed, when you hold the gun up to the light, you should see an even light space between the end of the ER and the lug of about 1/64". Look for rub marks in the bluing on the back of the lug around the locking bolt.

Also with cylinder open, and the cylinder pin pushed in all the way flush with the extractor star, the pin and the ER should be flush. Check too if the end of the ER is perfectly square. I think you're right, the ER may be just a tad too long but it's usually hard to open the cylinder if it is. You can also check if the ER by itself out of the cylinder revolves easily around the locking bolt when turned with your fingers.
 
I don't think I'd call removing the pin tricky, it does require a cup tip punch but pushes out like any other pin.

Does the locking bolt show a groove being worn into it by the ejector rod?

Does the end of the ejector rod have a square inside corner? If so breaking the corner with a countersink can help.

I fit center pins so they protrude from the ejector rod .010" or .015" rather than sit flush. Cylinder opening is easier, the locking bolt is less likely to "catch" on the ejector rod.

I think .030"-.040" between the ejector rod and barrel lug is more common than 1/64".
 
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tomcatt51 said:
I don't think I'd call removing the pin tricky, it does require a cup tip punch but pushes out like any other pin.

Does the locking bolt show a groove being worn into it by the ejector rod?

Does the end of the ejector rod have a square inside corner? If so breaking the corner with a countersink can help.

I fit center pins so they protrude from the ejector rod .010" or .015" rather than sit flush. Cylinder opening is easier, the locking bolt is less likely to "catch" on the ejector rod.

I think .030"-.040" between the ejector rod and barrel lug is more common than 1/64".
Click to expand...

Great advice. But the pin can be very tight and the punch tends to jump off. I always soak a bit with penetrating oil. And the gaps on my .32s actually measure an average .011", a little less than 1/64".
 
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Fixed. Thanks for help! Used hand drill and a round file to enlarge the ER hole.

6325282852_eda3e33806.jpg
 
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Wonderful. Glad to hear it's running like it should be, great little guns. I love my sq butt 3" like yours, although it's an I frame from 1955.
 
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