There are two methods.
The FACTORY method, which is the only one really approved, is the collar swaging/stretch method.
In this method a hardened steel support "spud" is inserted into the center of the cylinder where the crane fits.
A special hydraulic "jaw" device is fitted over the collar on the front of the cylinder and the device "pinches" or compresses the collar.
The cylinder is rotated and squeezed until there is a reduced "step" on the entire diameter of the front of the collar.
This produces a reduced diameter on the front of the collar which is how previously stretched collars are identified.
Then, the now longer collar is refit by using a milling machine to trim it to length.
This is a ONE TIME fix for cylinder end-shake, since the collar work-hardens and reduces the thickness the collar, a second attempt will crack it.
Also, due to the short length of the collar, it's not possible to get a second "bite" on the collar with the tool jaws.
The second, non-factory method is used as a restoration method on guns in which the collar can't be stretched for some reason, and the original cylinder needs to be retained.
In this method a lathe or milling machine is used to bore out the front of the cylinder to a larger diameter, removing the collar in the process.
A hardened steel bushing is made up and press-fitted to the larger hole.
This is then trimmed to length with the mill.
In this method, the new collar bushing is fairly short, and is similar to the pressed-in collar's used on S&W revolvers.
In these other guns, the bushing collar is nothing more than a bearing for the crane or yoke, since these guns don't space on the collar like the Colt's do.
This method works very well, and the bushing can be replaced if further end-shake appears.
The only requirement is the boring MUST be done in a highly precise, very exact way and based on the inner diameter of the original collar, NOT on cylinder diameter.
This is due to the fact that dead-center of the cylinder is based on the inner surface of the collar, NOT on cylinder diameter.
The factory-approved collar swaging method is done by both Colt, and at Pittsburgh Handgun Headquarters.
The other is best done by an absolutely crack pistolsmith/machinist who's had experience at doing the job.
In general, the first choice is a cylinder collar stretch, due to the lower cost of having it done.
The bushing method should be reserved for guns that have already been stretched, for cylinders that have damaged collars, or collars too short to be stretched beyond the .006 to .008 maximum stretch limit.
Because of the cost and difficulty in finding a QUALIFIED 'smith to do a bushing job, the stretch method is preferred for guns that can be stretched.
Due to the Colt design, it's not possible to do a simpler yoke tube stretch or washer job like on the S&W.
Thank you. I had seen the washers and yoke tube stretching mentioned for S&Ws, but nothing for Colt. I thought it might have something to do with the end of the tube and the slotted insert in the rear of the cylinder for the ejector rod. I have a rather rough (previously rusted, thus pitted) crane from which I can't remove the bushing. Wondered if beating it up a little was going to affect a critical dimension. Fortunately, I believe, I have a supposedly good condition replacement assembly on the way at a good price. Thanks again.
Not sure I understand: You have a Colt double action with some sort of bushing stuck on the crane????????
Also, please note that revolver cylinder and crane parts and assemblies are NOT "drop-in".
They MUST be properly fitted since everything, including headspace, end-shake, barrel/cylinder gap, and timing MUST be properly adjusted for proper function and accuracy.
This is one weakness of revolvers over autos.
Autos are such that MOST parts require as little fitting as possible, and many are true "drop-in".
Revolvers are "old school" in that even modern designs REQUIRE hand fitting and adjusting of many parts, and the cylinder assembly in particular.
This gets many people in trouble when they assume they can just order a part and drop it in.
The problem is compounded when you get USED parts, since these parts have ALREADY been fitted and adjusted for a different gun.
PITA it is. I've actually had to repair the wrench several times. I have Kroiled it pretty well, but I'm like the kids in the back seat - is it loose yet? Is it loose yet? I really think it is rusted permanently and that is why the "bag o parts" may be the only solution. It includes the crane and cylinder assembly and most if not all the internals. Actually the assembly I have is quite pitted on the cylinder shaft and somewhat in the chambers, so I'm probably better off except for fitting problems. We'll see and thanks again.
Dfariswheel especially, FWIW (and possible comment):
Received my bag o parts, apparently from Cobras /Agents but obviously not from stripping down the same gun - more like a collection from a gunshop or gunsmith estate. Included a looks-like-unfired cylinder and crane assembly which does seem to drop in reasonably well as far as I can tell so far. Only reason I can imagine why this was removed from a gun ( it is serialized) is that the lead ins are machined like washboards and you can feel the bolt dragging a little in DA. The hammer assembly (looks new) is one with the roll pin for the firing pin, trigger is grooved. My original internals seem to function quite well with the replacement cylinder, but substituting other parts brings up some fitting problems (as you know). Anyway, all of the parts are excellent, the price was right and it's interesting.
I think I have run out of options on that crane and may do it just to do it. I find that the second hammer works well enough but (again as I'm sure you know) the bolt, rebound lever and hand are a different story.
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