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09-16-2014, 09:26 AM
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S&W Model 10-5 Missaligned cylinder and cylinder-barrel gap issue
Hello everyone! First post here on the S&W forums. I stumbled on yall's FAQ and it is fantastic for the S&W revolver. I have a problem though with my Model 10 that I cannot figure out. I bought the gun cheap and bought it as a project, so I'd like to figure it out.
One of the cylinder chambers has a high spot in the gun causing it to seize when firing more than 30 or 40 rounds.
The cylinder-barrel gap goes from being approx 7 thou to 2 thou. There is no endshake. The timing on the revolver also tends to be a little bit slow (not terrible) on the one side of the cylinder.
Here's what I think it is NOT :
- A misaligned cylinder yoke. If this was the case, the high spot would not travel with the cylinder. The same would go for the timing of the revolver.
- A crooked or non-square barrel face. Again, just like above, the cylinder would be tight the whole time.
This is what puzzles me though... the cylinder face is ground within 1 thou, meaning that it is not uneven, so some other surface that the cylinder bears on IS. Getting this fixed by S&W will probably cost over 100 dollars, and that was never my goal in the beginning. I wanted to learn a bit more about revolvers.
What I'm asking is really what's wrong and what could I attempt to do? Access to machine tools is no issue, its really a mater of determining what's actually wrong.
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09-16-2014, 09:39 AM
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10
you find some revolvers that don't time up correctly on some of the chambers,due to the rachet being worn and the hand, most time a new hand from brownell's will fix but must be fitted but it is eazy most metal will be removed from the side of the hand.
as far as the cylinder dragging on the barrel the endshake bering from brownell's will cure that also, I have fixed a lot of them with the same problems.
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09-16-2014, 09:55 AM
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I considered a new hand, that may solve the timing issue, but again, its just the slightest bit slow, not really even an issue.
I also considered en shake bearings, but there's no end shake to eliminate? The cylinder might move by a thousandth or two either way when in the gun.
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09-16-2014, 11:24 AM
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You might want to check the cylinder notches under magnification for burrs etc. Also look over the ratchet the same way. Also it is possible that the end of the yoke is square and the bottom of the cylinder is not. Or maybe even both are a bit off and when the high spots align you drag a bit. Rotate the cylinder on the yoke pressing forward gently and check the tiny gap where the front of the cylinder's center meets the yoke assy for changes. Is your ejector rod perfectly straight? Roll it on a piece of flat glass slowly if you don't have a precision granite block.
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09-16-2014, 11:37 AM
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I did buff out burs on the rachet under a microscope. I also measured it and noticed no high spots. The ejector rod is straight, It's within .001" when spun on a lathe chuck. I did notice on the front of the cylinder where the cylinder meets the yoke, that there was a high spot, so I machined it down. It was only a couple thousandths. I observed no change in measurements elsewhere on the gun afterwards as that surface doesn't seem to bear on anything.
The only place I can think of left is where the yoke and ejector rod thread together. Could there be a high spot there and or are there simple fixes/part swaps that might solve the issue?
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09-17-2014, 08:28 AM
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How did you measure the forward face of the cylinder to determine it is machined within .001 ? Did you mount it on an arbor and rotate it to measure runout? You may need to MAKE an arbor to measure this OR use an old yoke mounted in a small machine vise on a surface plate. Or, the runout could be measured with an arbor mounted in a lathe (not running) with the tailstock keeping the cylinder moving while measuring the runout.
I dont see how any of the other suggestions could change barrel/cylinder gap. The front face of the cylinder must be NOT perpendicular (not square) to the axis bore in the cylinder's center. I had a model 25-2 that was out of square but not by as much as you reported.
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09-17-2014, 10:18 AM
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I used a lapped surface plate and a dial indicator and determined the two cylinder faces are both parallel and ground precisely. To determine that the cylinder is not rotating properly, I mounted the gun and used the same dial indicator to measure the cylinder.
I've also chucked it up on a non running lathe and measured using a dial indicator.
After seeing that the cylinder faces are not out of spec, It makes me think that the axis bore in the cylinder's center has something wrong with it. I'll need to do some more measuring on it too.
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09-17-2014, 10:26 AM
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I'm no pistolsmith, but I did sleep at a Holiday Express (not really). It sounds a lot like a sprung yoke. The uninitiated like to flip those cylinders closed with one hand to look cool. Hey, they still do it in the movies.
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09-17-2014, 11:14 AM
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A sprung yoke would cause the misalignment to remain close to constant on all the chambers.
Have you checked the yoke to make sure the end that goes inside the cylinder is sq.? But this would also cause a steady misalignment hole to hole. But if the bottom of the cylinders center hole that mates to this surface was out of sq or had some kind of defect it would cause the cylinder to changes its gap aliment as it rotated. With the tools at your access and the machine knowledge you showing you should be able to figure out how to check it and even make a tool to take care of it.
But K frame cylinders are pretty available on gun broker and probably ebay.
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09-17-2014, 08:07 PM
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I'm going to attempt to diagnose and fix this thing. If push comes to shove, Ill go and buy a spare cylinder, those things are a dime a dozen.
I'll post updates as I learn more and get to the bottom of this. If anyone has more suggestions, I'll gladly listen! I'm no machinist and I'm certainly not close to knowing nearly enough about gunsmithing nor machining. Just trying to learn it while I'm young!
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09-17-2014, 08:57 PM
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Have you checked for slop in the yoke to cylinder fit? Wear on the yoke or cylinder might line up on a certain chamber as the cylinder rotates and cause a drag. I am referring to side to side or up and down slop not front to rear. Had a British pre victory that had that problem. If the problem shows up after that many rounds check for slop when it is hot.
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09-17-2014, 10:12 PM
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There is a little bit of slop in the cylinder side to side on the yoke. How did you solve the issue? I imagine that the yoke could be modified but it may be worth getting a new one at that point.
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09-17-2014, 11:08 PM
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You note an availability of machine tools. Much of what you're looking for is in fine fitting, not machine work.
1. Before proceeding further, the yoke needs to be checked for proper alignment with an alignment spud. If the spud won't drop into the center pin hole in the breech with the yoke closed, you have a bent yoke. Is the end of the yoke barrel perpendicular to its bore?
2. You've checked endplay. What's the headspace? Assuming no burrs around the firing pin bushing/hole on the breech, the breech to rear cylinder face should be 0.060-0.066 inches. BTW, the space beneath the ejector star is clean and free of burrs?
3. If you're noticing binding while the cylinder rotates, have you checked the front locking bolt and end of the extractor rod for issues? The rod may be straight, but if the bevel on the inside of the rod isn't centered, you may have issues. I've replaced more than one locking bolt for being badly machined.
4. If you're still having issues, might be the yoke bore at the center of the cylinder. The facing of this bore at the bottom may be grooved. This is getting to factory type work here.
You may find used yokes around, there's no telling what condition they're in. New yokes are strictly factory/authorized service center/certified armorer items. I supose you could sleeve the yoke bore in the cylinder, but his would require loads of slop and/or a willingness to risk the cylinder to sleeve it.
Last edited by WR Moore; 09-17-2014 at 11:12 PM.
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09-18-2014, 08:04 AM
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I used hardened shim stock to sleeve the cylinder. It springs to fit the cylinder and tightened the fit to where there was free rotation and slop was barely perceptible. There was no groove from the yoke but I think you can get a tool that will take that out and use the shims available to fix any front to rear problems. I think it would take a lot of shooting to wear the shims out. Inexpensive to try at least.
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Last edited by vonn; 09-18-2014 at 08:05 AM.
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09-19-2014, 09:42 AM
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Quote:
Originally Posted by ct241
Hello everyone! First post here on the S&W forums. I stumbled on yall's FAQ and it is fantastic for the S&W revolver. I have a problem though with my Model 10 that I cannot figure out. I bought the gun cheap and bought it as a project, so I'd like to figure it out.
One of the cylinder chambers has a high spot in the gun causing it to seize when firing more than 30 or 40 rounds.
The cylinder-barrel gap goes from being approx 7 thou to 2 thou. There is no endshake. The timing on the revolver also tends to be a little bit slow (not terrible) on the one side of the cylinder.
Here's what I think it is NOT :
- A misaligned cylinder yoke. If this was the case, the high spot would not travel with the cylinder. The same would go for the timing of the revolver.
- A crooked or non-square barrel face. Again, just like above, the cylinder would be tight the whole time.
This is what puzzles me though... the cylinder face is ground within 1 thou, meaning that it is not uneven, so some other surface that the cylinder bears on IS. Getting this fixed by S&W will probably cost over 100 dollars, and that was never my goal in the beginning. I wanted to learn a bit more about revolvers.
What I'm asking is really what's wrong and what could I attempt to do? Access to machine tools is no issue, its really a mater of determining what's actually wrong.
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I have a question. Does it bind after shooting a several cylinders worth of ammo? I had this problem in a SW 625 JM. It turned out that it was a loose extractor rod housing. It had become loose when firing and started backing off (unscrewing) until it finally pushed the cylinder back against the inside face of the revolver housing. I'd tighten it up finger tight, but it invariably work itself loose after a couple dozen rounds and I finally removed the extractor rod housing from the star extractor/cylinder yoke and looked at it very carefully. With a small fine detailing swab (very tiny) I put some locktite on the very few threads where it locked everything down and put it back on. I haven't had the problem since, but you have to be very very careful where you put the Loctite.
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09-20-2014, 08:23 AM
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WR Moore: I will look into all of these as possible problems/solutions, thank you for the detailed advice. I won't be able to mess with the thing while being out of town for the weekend.
vonn: That's an interesting fix, I don't think I have enough room in there all around for a shim but I might experiment with some loose stuff laying around!
Gaffer: Yes it does bind after around 30 to 40 rounds. The extractor rod housing stays pretty tight even after a day of shooting. Some temporary loctite might not be a bad idea once I get this thing together.
I also found a complete cylinder, crane, extractor and extractor rod assembly on ebay for 40 bucks. This will give me some parts to play around with! It might even fix my problem altogether! I'm also going to machine a yoke alignment tool. While I don't think this is the issue, It won't hurt to have one!
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09-23-2014, 10:36 PM
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Hey everyone!
Well I think I fixed the problem! I bought a used cylinder on ebay, put it on my current crane and it fit like a glove! barrel-cylinder gap comes out to a CONSTANT .008"! A little high, but safely within recommended ranges of the gun! The new cylinder also looks brand new, which on the gun looks odd as there is no finish left whatsover on the frame and barrel.
I now plan to slow rust blue the gun and refinish some used wood grips that I got for it! My goal is to make the gun look brand new! I'll post pictures at some point prior to starting the project!
Thanks everyone for the advice! I may still try to figure out what the problem with the old cylinder was. The bore going down the cylinder looks a bit rough and I want to check that the bore axis is perpendicular to the face of the cylinder. If it isn't I may try to lap it to be correct.
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09-24-2014, 09:05 AM
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Glad you worked it out. Was pretty sure the problem was with the cylinder as with a good cylinder and a bad forcing cone or yoke the problem would remain fairly constant for all positions of the cylinder.
I have had fairly good luck replacing cylinders. Usually some, but not much fitting required. A junker model 10-2 I bought long ago, with a split forcing cone, now sports a new barrel and a recessed 357 cylinder and adjustable sights. Shoots very well.
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09-25-2014, 06:03 PM
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Can you swap in a 357 cylinder and fire it safely through a Model 10? Or did you put a barrel marked "357" on the model 10 frame.
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09-25-2014, 07:34 PM
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The barrel was a replacement model 10 barrel. I put a model 19 cylinder in it and fire 357 mags in it. Well over 500 rounds with no change in end shake. If the frame wasn't going to take it the pressure would stretch it length wise. I have never seen a top strap that let go without the cylinder going first. I also milled the top strap and drilled and tapped to accept S&W rear sight assy. I believe you could ream a model 10 cylinder to 357 but, I used one from a model 19 and if it don't blow in a model 19 why would it get weaker because I put it in a model 10??? I had to cut the forcing potion of the barrel to clearance the slightly longer cylinder and redo the forcing cone. I also had to relive the frame lug some for the recessed cylinder to clear. The model 10-2 when into production in 1961. If S&W hadn't figured its 4140 heat treat out by then they still wouldn't have. It makes absolutely no sense to HT one group of frames different than another. It certainly wouldn't save money to do an inferior heat treat. The superior HT some talk about is simply speculation by those who know little about HT. I do my own HT on a variety of steels mostly making custom knives. 4140 is rather simple to HT by the way. I do find a lot of the 357, 44 mag frames have a special HT a bit more difficult to believe because ordinance quality stainless steels can't come close to the tensile strength of 4140 no mater how its heat treated. How many of those have you seen blown up by anything other than stupidity. I do believe that prior to WWII S&W may not have had the best HT, but equipment and knowledge went a long way in that period. I have also done hardness test on every S&W frame I own and every one of them comes out within a couple points on the Rockwell B scale. Way to soft for Rockwell C. By the way they have Rockwell Bs in the same range as mild steel. Yup relatively soft.
Just my opinions and beliefs. I wouldn't do it to someone elses revolver. But, it was a test of my beliefs and I have seen nothing that disproves them with this modified revolver.
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09-27-2014, 05:32 PM
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That is really cool! I'm fairly certain that I read that early on they did chamber some Model 10s for .357 mag, but then swiched to a model 19 designation. This could be totally wrong of course, but I thought it was interesting. I imagine that if it worked for that early batch it should work for future revolvers. It would be foolish to have two separate batches of frames and let one get improper heat treatment and the other get a slightly better one.
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09-28-2014, 07:24 PM
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Another thing that makes me believe all frames would receive the same HT is that they must be finish machined after the HT in that HT causes small dimensional changes in the piece as the carbon and iron atoms are rearranged during HT as the crystal like matrix is reformed(sorry no such thing as a steel molecule). Thats when they would machine things like side plate joints, adjustable sight grooves etc. Having inventories of differently HT J, K, Land N frames would be a nightmare to track through the various machining processes.
I remember some one being against machining a frame to accept ajustable sights. Now why would it matter is I did it or S&W did it. If you take a K frame and machine it to accept adjustable sights It will measure the same as a factory one. When I did it I used a factory adjustable sight K frame to get the measurements to make my cuts on the model 10 frame.
The are revolvers not some super secret spy plane.
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