Ok so after roughly a 2 month trip back to S&W for a new barrel I put 100+ rounds of .38 special and 4 rounds of .357. Felt comfortable enough to send off my cylinder to J.D. at Original Precision for a moon clip cut. I had the frame sitting on my desk sans cylinder and saw it was shiny and kind of rough on the end. I thought maybe I'd knock down the edge and polish it. When I went to wipe it off with the paper towel after rubbing it lightly with some lapping film it caught? Being a blind 54yr old I pulled out my USB microscope and found it was cracked in several places around the end. I just can't catch a break with this thing. Check out the pics and let me know what you think. I couldn't even find the yoke to purchase at Midway or Brownell's.
340PD is jinxed... Crane/Yoke
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stress cracks
The indentations around the end of the yoke barrel appear to be attempts at stretching the yoke with a tool designed for that purpose. Repeated use of the yoke stretching tool however, has caused the cracks that appear in the yoke barrel's end.
Another possibility is the improper stretching rendered the yoke barrel so thin on the end, that is was damaged by impact stress during firing.
This tool is used as an alternative to other methods of making the yoke barrel longer, like peening, or adding yoke shims, in order to alleviate excessive end shake.
Opinion: the stress cracks were caused either by repeated and improper use of the tool, or using the tool without first inserting a yoke liner into the yoke tube, and/or impact stress during firing.
Obviously, a new yoke will need to be fit.
Yoke stretching tool....
The indentations around the end of the yoke barrel appear to be attempts at stretching the yoke with a tool designed for that purpose. Repeated use of the yoke stretching tool however, has caused the cracks that appear in the yoke barrel's end.
Another possibility is the improper stretching rendered the yoke barrel so thin on the end, that is was damaged by impact stress during firing.
This tool is used as an alternative to other methods of making the yoke barrel longer, like peening, or adding yoke shims, in order to alleviate excessive end shake.
Opinion: the stress cracks were caused either by repeated and improper use of the tool, or using the tool without first inserting a yoke liner into the yoke tube, and/or impact stress during firing.
Obviously, a new yoke will need to be fit.
Yoke stretching tool....
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That is a real bummer.
Since you have sent the cylinder off to be modified I will be surprised if S&W will warranty the gun. Good revolver gunsmiths are getting bard to find and likely backed up on work.
I haven't looked lately but I have seen J-Frame cylinders and yokes on eBay fairly frequently in the past. I don't think that is the best solution for your problem but it may be the only solution shy of sending it back to the mothership at great expense and a long delay to replace it. I just checked the yoke on my 360J and sure enough a magnet sticks to it so it appears that they are steel, but maybe the 340 uses an aluminum yoke. Had it been me, I think I would have picked up a SIG P365 with its rapid reloading capability, and safety if you want, versus moon-clipping a J-frame. Understand this is S&W Forum but there are some pretty slick solutions out there available as an alternative to a J-frame. Pretty sure a P365 is kind of like a 1911, you can throw it through a plate glass window, pick it up on the other side and continue to use it.
Luckily cylinder is NOT cut and is still enroute to JD. The gun will be stock going back to S&W except for a XS front sight.
I appreciate the response, I did give a try to the 365 and it's a decent option, I vastly prefer my G43 over it. I have plenty of carry guns for the rotation I just really wanted one of these to work.
I appreciate the response, I did give a try to the 365 and it's a decent option, I vastly prefer my G43 over it. I have plenty of carry guns for the rotation I just really wanted one of these to work.
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The indentations around the end of the yoke barrel appear to be attempts at stretching the yoke with a tool designed for that purpose. Repeated use of the yoke stretching tool however, has caused the cracks that appear in the yoke barrel's end.
Another possibility is the improper stretching rendered the yoke barrel so thin on the end, that is was damaged by impact stress during firing.
This tool is used as an alternative to other methods of making the yoke barrel longer, like peening, or adding yoke shims, in order to alleviate excessive end shake.
Opinion: the stress cracks were caused either by repeated and improper use of the tool, or using the tool without first inserting a yoke liner into the yoke tube, and/or impact stress during firing.
Obviously, a new yoke will need to be fit.
Yoke stretching tool....
Interesting production tool to stretch cranes
I've always done it the old fashioned way with an inner support mandrel and slow easy working with small a ball pein hammer while rolling on an anvil
I just modified a tubing cutter years ago (1980) by carefully grinding the cutting wheel down so that there is an appropriate width flat on the wheel instead of the sharp cutting edge.
After inserting the yoke liner inside the yoke barrel, the tool is placed on the yoke barrel and tightened/turned in increments to compress and elongate the barrel. After using this tool for decades, I believe the shims are a better solution. Unfortunately, shims were not available for this particular purpose back in the last century, so peening was the only option.
After inserting the yoke liner inside the yoke barrel, the tool is placed on the yoke barrel and tightened/turned in increments to compress and elongate the barrel. After using this tool for decades, I believe the shims are a better solution. Unfortunately, shims were not available for this particular purpose back in the last century, so peening was the only option.
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I am a fan of the shims myself. Putting in a hardened bearing surface tops stretching. J frame shims are a bit harder to find. I second trying to get another yoke and fitting it. But, the newer magnum length J frame yokes have the gas ring on the cylinder, not the yoke. My 32 H7R 431 had an alloy yoke with steel tube and it had a separate gas ring not press into cylinder not mounted on gas ring, my 357 and 2 newer 38 spec alloy J frames came with steel yokes that have what functions as the gas ring on them
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The first time I heard a description of stretching the yoke barrel I thought I was getting my leg pulled. When you stretch the yoke barrel that way, you're reducing the cross sectional area of the yoke barrel. This makes it much more likely to collapse and you end up with the same excess end shake you started out with.
Official method or not, I think the shims are the best way to go. Worst case, you can always replace the shim(s).
I once worked on a model 28 converted to .45 ACP by a famous name gunsmithing shop. I noticed excessive endplay and went to shim it. After a whole pack of shims didn't solve the problem I broke out the measuring tools. I ended up making a hardened tool steel bushing 0.055 in thick to keep the cylinder where it needed to be. OD/ID like the shims.
That might be a way to solve the current problem. Cut the current yoke barrel shorter and then bush the ejector rod bore.
Official method or not, I think the shims are the best way to go. Worst case, you can always replace the shim(s).
I once worked on a model 28 converted to .45 ACP by a famous name gunsmithing shop. I noticed excessive endplay and went to shim it. After a whole pack of shims didn't solve the problem I broke out the measuring tools. I ended up making a hardened tool steel bushing 0.055 in thick to keep the cylinder where it needed to be. OD/ID like the shims.
That might be a way to solve the current problem. Cut the current yoke barrel shorter and then bush the ejector rod bore.
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On the rare occasion I've had to fix an end shake issue, shims (.001" & .002") were used rather than the "tubing cutter" method. I never cared for stretching because it weakens the metal and could also shrink back down. The use of shims is a way better method in my experience. I'll leave the tubing cutter for plumbing jobs-lol.
Sorry for your woes and hopefully your GS will step up and do the right thing! Hopefully you can find the part. Try Numrich GP's, Jack First, Bob's, or eBay.
Sorry for your woes and hopefully your GS will step up and do the right thing! Hopefully you can find the part. Try Numrich GP's, Jack First, Bob's, or eBay.
Doubtful you will find a new yoke since that is considered to be a fitted part and S&W does not sell them. When I went to the factory school the yoke adjustment was done by peening with a hammer… As I recall, they were testing the yoke stretching tool but had not adopted it for the assembly fitters and it was not offered to us in the tool kit. I believe the shims are a better idea for a more precise adjustment.
No I meant it's going to go back to S&W for a yoke.
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Given the quality of a lot of hired help these days, you might want to refer to the part as the "yoke". "Yoke" is S&W speak, "crane" is Colt speak for the part in question. Ya don't want to confuse the poor souls.
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