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01-16-2013, 11:30 PM
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Forcing Cone/Cylinder Contact Opening/Closing
Model: S&W 586 .357 magnum 4" 6 shot, 1982 make
I've got a problem with my S&W that's been really bothering me. This gun is still practically new with less than a hundred rounds down the barrel, mostly .38's. I think this is a highly unusual problem but hopefully someone here can assist me.
Problem: The cylinder appears to be scraping against the forcing cone ONLY when opening and closing the cylinder. I felt it a little at first opening and closing the cylinder. After doing a little shooting there was normal carbon build up on the forcing cone. After opening and closing the cylinder a few times I could see the cylinder scraped off carbon where I guess the high spots are. Please advise! Thank you!
Specs: Using different types of paper and my reloading caliper - in essence making my own feeler gauge - I have determined that the gap is neither .005 inches nor .008 inches but somewhere in between. From what I understand, this is both acceptable and within tolerances.
When the cylinder is CLOSED, the cylinder moves forwards and rearwards .002 inches which is very minimal.
This being said, when I open the cylinder (say to load rounds) there becomes a lot of noticeable play rearwards and forwards with the cylinder itself. I measured this movement and found it to be able to move roughly .0185 inches. Having looked at it again just now, it apears that the only thing stopping the cylinder from moving even farther rearwards in the open position is that outcropping of metal on the frame.
The last measurement is the movement between the yoke assembly and the frame. It is extremely minimal that I couldn't even measure it. I would say less than .001 inches.
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01-17-2013, 01:14 PM
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All of what you describe is normal. The outcropping of metal you mention is the only thing holding the cylinder in place when open. If you remove the forward most sideplate screw, the cylinder and yoke slide right off and the cylinder will then slide off the yoke. The only time you need to be concerned is when the cylinder is closed. If the cylinder moves too much fore and aft (endshake), then you should address the problem.
Good luck,
Steve
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01-17-2013, 06:32 PM
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Quote:
Originally Posted by w0lfattack
After doing a little shooting there was normal carbon build up on the forcing cone. After opening and closing the cylinder a few times I could see the cylinder scraped off carbon
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Normal. You say you have ~.005"-.008" barrel/cylinder gap and ~.002" cylinder endshake, so, if you have more than ~.005" carbon build-up it will scrape. Normal.
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01-19-2013, 12:31 AM
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Quote:
Originally Posted by USBP SW
All of what you describe is normal. The outcropping of metal you mention is the only thing holding the cylinder in place when open. If you remove the forward most sideplate screw, the cylinder and yoke slide right off and the cylinder will then slide off the yoke. The only time you need to be concerned is when the cylinder is closed. If the cylinder moves too much fore and aft (endshake), then you should address the problem.
Good luck,
Steve
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Thanks for the response. So are you saying it doesn't matter if the cylinder is scraping against the forcing cone when I open and close it?
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01-19-2013, 11:27 AM
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Quote:
Originally Posted by w0lfattack
After opening and closing the cylinder a few times I could see the cylinder scraped off carbon
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Quote:
Originally Posted by w0lfattack
it doesn't matter if the cylinder is scraping against the forcing cone when I open and close it?
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If you're just scraping off carbon, it's normal.
The cylinder endshake/barrel cylinder/yoke clearance/endshake specs you listed, if correct, should not allow appreciable metal to metal contact.
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01-19-2013, 05:53 PM
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Quote:
Originally Posted by tomcatt51
If you're just scraping off carbon, it's normal.
The cylinder endshake/barrel cylinder/yoke clearance/endshake specs you listed, if correct, should not allow appreciable metal to metal contact.
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Well it's scraping off more than just carbon. There is bare metal showing where it contacts the cylinder and bluing where it doesn't. It is indeed hitting the forcing cone. It has created a light burr along the edge where the cylinder first contacts the forcing cone.
Regardless of my specs (lets just assume they're in accurate), should I be concerned and can I fix it with some of these bushings I've heard about?
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01-19-2013, 06:53 PM
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Quote:
Originally Posted by w0lfattack
It has created a light burr along the edge where the cylinder first contacts the forcing cone.
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A "light burr" on the edge of the barrel? If so, that is also quite normal. A left-over from the barrel/cylinder gap being set during assembly. They all have it, some enough it can cut your finger. As for the cylinder face, a "ring" around cylinder throats after the gun sees some use is also normal.
If you want more meaningfull help spend a couple bucks and buy a set of feeler gauges to check clearances with. It really sounds like you're obsessing.
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01-19-2013, 08:08 PM
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Quote:
Originally Posted by tomcatt51
A "light burr" on the edge of the barrel? If so, that is also quite normal. A left-over from the barrel/cylinder gap being set during assembly. They all have it, some enough it can cut your finger. As for the cylinder face, a "ring" around cylinder throats after the gun sees some use is also normal.
If you want more meaningfull help spend a couple bucks and buy a set of feeler gauges to check clearances with. It really sounds like you're obsessing.
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The problem is the burr is not from manufacturing. I've seen this burr raise slowly from normal operation. There is also a normal "ring" around the cylinder throats and I understand that this is normal. However, it is the fresh scraping marks along all of the edges of the face of the cylinder that is causing me some concern.
Like I have said before, I am comfortable with my cylinder-forcing cone gap. When it is closed, it is fine. My concern is the rough contact the cylinder makes with the forcing cone when it opens and closes.
I am not trying to change the gap I have when its closed, I'm trying to keep from causing damage to the forcing cone.
I apologize for "obsessing" over a gun I plan on keeping for the rest of my life.
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01-19-2013, 09:36 PM
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OK, If there are "fresh scraping marks along all of the edges of the face of the cylinder", are they just scraping off carbon or are they metal to metal? How much yoke endshake do you have with the cylinder open? Closed, this should be established by the thrust surface on the yoke and frame. Open, it's controlled by the yoke screw and the "button on the yoke. This should be ~.002" on an "old style" gun that doesn't have the spring loader plunger in the yoke screw ( which I think yours is) and nil on a "new style" gun. Are you worried about someting that only happens as you close the cylinder?
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01-20-2013, 12:10 AM
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Quote:
Originally Posted by tomcatt51
OK, If there are "fresh scraping marks along all of the edges of the face of the cylinder", are they just scraping off carbon or are they metal to metal? How much yoke endshake do you have with the cylinder open? Closed, this should be established by the thrust surface on the yoke and frame. Open, it's controlled by the yoke screw and the "button on the yoke. This should be ~.002" on an "old style" gun that doesn't have the spring loader plunger in the yoke screw ( which I think yours is) and nil on a "new style" gun. Are you worried about something that only happens as you close the cylinder?
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I'm not sure I completely follow. Yes my concern is only when I am closing the cylinder.
When I start to close the cylinder, the edge of the cylinder face strikes the forcing cone removing bluing from the forcing cone and from the cylinder face. Once the cylinder is completely closed, the gap is as it should be. It doesn't make any sense.
The end shake of the cylinder when it is opened is .0185" (refer to original post).
I do not know whether or not I have an old style gun. Like I said, it is a S&W 586 made in 1982. From what I hear, it is the same as the 686 but instead of stainless, it is blued. How do I find out if I have a spring loaded plunger in my yoke screw? Is this the screw that goes into the side plate by where it says "Made in the USA"?
I greatly appreciate your assistance!
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01-20-2013, 12:18 AM
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Quote:
Originally Posted by w0lfattack
I'm not sure I completely follow. Yes my concern is only when I am closing the cylinder.
When I start to close the cylinder, the edge of the cylinder face strikes the forcing cone removing bluing from the forcing cone and from the cylinder face. Once the cylinder is completely closed, the gap is as it should be. It doesn't make any sense.
The end shake of the cylinder when it is opened is .0185" (refer to original post).
I do not know whether or not I have an old style gun. Like I said, it is a S&W 586 made in 1982. From what I hear, it is the same as the 686 but instead of stainless, it is blued. How do I find out if I have a spring loaded plunger in my yoke screw? Is this the screw that goes into the side plate by where it says "Made in the USA"?
I greatly appreciate your assistance!
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It sounds like you are trying to say that the forward edge of the cylinder is striking the barrel shank (not the forcing cone) when you try to close the cylinder. If I understand your post correctly - and I am not sure that I do - it does not sound right, and I would call S&W.
It might help if you post pictures.
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01-20-2013, 07:39 PM
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Actually, the yoke should prevent contact with the barrel extension even when partially open, just as it does when closed. Can you move the yoke back and forth at any point in its travel? Also, check to make sure that the cylinder does not contact the barrel extension when closed, this is what is refered to as endshake and is relatively easy to correct. If you can move the yoke forward, then that is a different problem and could cause what you describe. If the yoke moves, it could be as simple as replacing the sideplate screw or work on the groove that the sideplate screw rides in.
I hope you find your problem, let us know how it turns out.
Steve
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01-20-2013, 08:49 PM
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Quote:
Originally Posted by w0lfattack
When I start to close the cylinder, the edge of the cylinder face strikes the forcing cone removing bluing from the forcing cone and from the cylinder face. Once the cylinder is completely closed, the gap is as it should be. It doesn't make any sense.
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It makes sense. How much yoke endplay is there when the yoke is open?
When the yoke is closed there are thrust surfaces on the yoke and frame that limit yoke endplay. When the yoke is open, yoke endplay is controlled by the yoke "button" and the yoke screw, the "front" sideplate screw.
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01-21-2013, 01:17 AM
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Quote:
Originally Posted by shawn mccarver
It sounds like you are trying to say that the forward edge of the cylinder is striking the barrel shank (not the forcing cone) when you try to close the cylinder. If I understand your post correctly - and I am not sure that I do - it does not sound right, and I would call S&W.
It might help if you post pictures.
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I'm not sure what the difference is between the barrel shank and the forcing cone. I've tried taking pictures but nothing really comes out. I will continue trying or find another camera.
Quote:
Originally Posted by USBP SW
Actually, the yoke should prevent contact with the barrel extension even when partially open, just as it does when closed. Can you move the yoke back and forth at any point in its travel? Also, check to make sure that the cylinder does not contact the barrel extension when closed, this is what is refered to as endshake and is relatively easy to correct. If you can move the yoke forward, then that is a different problem and could cause what you describe. If the yoke moves, it could be as simple as replacing the sideplate screw or work on the groove that the sideplate screw rides in.
I hope you find your problem, let us know how it turns out.
Steve
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Yes, I can move the yoke forwards and rearwards starting about midway between being completely open and completely closed. The cylinder does not contact the "barrel extension" when it is completely closed. The cylinder only contacts the barrel extension in the process of closing the cylinder.
Quote:
Originally Posted by tomcatt51
It makes sense. How much yoke endplay is there when the yoke is open?
When the yoke is closed there are thrust surfaces on the yoke and frame that limit yoke endplay. When the yoke is open, yoke endplay is controlled by the yoke "button" and the yoke screw, the "front" sideplate screw.
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I think I understand what you are saying. Is the forward most screw the yoke screw? What is the yoke button? Are these the items that need to be adjusted or fixed for my particular problem?
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01-21-2013, 11:05 AM
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Quote:
Originally Posted by w0lfattack
Yes, I can move the yoke forwards and rearwards starting about midway between being completely open and completely closed. The cylinder does not contact the "barrel extension" when it is completely closed. The cylinder only contacts the barrel extension in the process of closing the cylinder.
I think I understand what you are saying. Is the forward most screw the yoke screw? What is the yoke button? Are these the items that need to be adjusted or fixed for my particular problem?
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Yes the "yoke screw" is the "forward most" sideplate screw, it's "under the cylinder". Remove it and you can remove the yoke, slide it forward, and the cylinder assy.
On the yoke, the part that was in the frame, you'll see a groove. The metal after the groove is called the "button" and it and the screw end control yoke endplay when the yoke is open.
Check the sideplate screws. One (or more) will have a tip that is straight, no threads. A srew with a straight, no threads, tip is the yoke screw. If the wrong screw is used as the yoke screw you will have excessive yoke open endplay. That straight tip contacts the button setting endplay.
The bad part is that yoke open endplay is literally adjusted with a hammer. Peening and filing the "button" to set yoke open endplay.
Install the yoke only, no cylinder assy, without the yoke screw in place. Close the yoke and you'll be able to see the frame and yoke thrust surfaces that limit yoke endplay with the yoke closed.
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01-21-2013, 11:23 AM
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Make a GREAT INVESTMENT.
Buy Jerry Kuhlhausen's S&W Revolver Manual.
It's full of explanations, photos, and remedies, I wouldn't be without it.
Well Worth the $30.
__________________
NRA Pistol/Rifle Inst. RSO
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01-21-2013, 11:50 AM
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Quote:
Originally Posted by w0lfattack
I'm not sure what the difference is between the barrel shank and the forcing cone. I've tried taking pictures but nothing really comes out. I will continue trying or find another camera.
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The "barrel shank" is that short portion of the barrel which extends through the frame (not the end where the front sight is located). Many mistakenly refer to the barrel shank as the "forcing cone."
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01-21-2013, 10:39 PM
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Quote:
Originally Posted by tomcatt51
Yes the "yoke screw" is the "forward most" sideplate screw, it's "under the cylinder". Remove it and you can remove the yoke, slide it forward, and the cylinder assy.
On the yoke, the part that was in the frame, you'll see a groove. The metal after the groove is called the "button" and it and the screw end control yoke endplay when the yoke is open.
Check the sideplate screws. One (or more) will have a tip that is straight, no threads. A srew with a straight, no threads, tip is the yoke screw. If the wrong screw is used as the yoke screw you will have excessive yoke open endplay. That straight tip contacts the button setting endplay.
The bad part is that yoke open endplay is literally adjusted with a hammer. Peening and filing the "button" to set yoke open endplay.
Install the yoke only, no cylinder assy, without the yoke screw in place. Close the yoke and you'll be able to see the frame and yoke thrust surfaces that limit yoke endplay with the yoke closed.
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Thank you for this info! I'm going to be looking for a gunsmithing screwdriver to take that screw out. If I find the task beyond my capability or understanding I will be sending it to a local gunsmith. Thank you so much for your help!
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01-22-2013, 07:18 AM
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I fully & completely understand what you're talking about :
I have the exact same phenomenon happening to my 4" 586 (I think same vintage as yours).
No gunsmith I ever showed it to seemed to understand any of it, nor deem it problematical.
Indeed, the gun functions fine.
It's only when closing it, that the outer surface of the cylinder hits the barrel's rear end.
Apart from some "finish damage", I never experienced any other consequence.
If & when you do dismantle all the parts mentioned (yoke etc.) & measure & inspect them I bet you'll find nothing wring with them.
What I did was stop worrying & shoot the hell out of my 586.
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01-22-2013, 07:20 AM
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oops... "nothing wrOng".. of course
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01-25-2013, 09:46 AM
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call smith and ask for a endshake screw for this mod.
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