Revolver Cylinder Bearings ?

[Hannibal]

If someone would be so kind, please help me understand cylinder bearings. When a revolver needs 'tightening up', either due to wear & tear, personal preference or perhaps it was not fitted tightly when new, the result can be endshake. I get that part. Endshake can be easily measured with feeler gauges. I get that part, too. The yolk can be loose and contribute to the issue. No problem understanding that, either.
Now, as for the cylinder. To tighten this area up, it appears the two options are stretching the yolk or installing bushings.
If one stretches the yolk, the cylinder is moved toward the barrel, correct? And if bushings are installed, the amount of endshake will be reduced, but you are shimming the cylinder to the rear, toward the hammer, correct?
Or is this a 6 of one, half-dozen of another proposition and BOTH methods shift the cylinder toward one direction, and if so, which way ?
I'm just trying to make sure I understand the whole issue correctly. If I'm off base here, PLEASE steer me straight.

Thanks!

[Mk42gunner]

Eliminating endshake by either method moves the cylinder to the rear. The worst thing about it is that to correct endshake, you have to increase the barrel to cylinder gap.

When I went through armorer's school, the instructor was adamant not to use bushings on a duty gun. He said they were okay for a range queen, but not for something that a persons life depended upon.

Robert

[Hannibal]

I see. Do you know what basis the instructor formed his opinion on?
I appreciate your response, and I do not dispute what you have said, I'm just trying to understand it as fully as possible.

Thank you !

[bhn22]

Do you have a Kuhnahusen S&W manual? The procedure is explained in detail there. Normally, you only have to do one or the other, stretch the yoke and face to the needed length, or face the yoke and shim to the needed length. Yes, it is possible that you may need to adjust the barrel cylinder gap when done, depending on the guns condition.

[Char-Gar]

Cylinder endshake occurs as the rear of the cylinder yoke gets battered by recoil after a time and the cylinder moves forward decreasing the barrel cylinder gap, until the cylinder finally rubs against the barrel root. The headspace between the rear of the case and the recoil shield also increase.

The bearing restores the original length of the yoke, moving the cylinder back, restoring the factory barrel/cylinder gap and headspace. It is a very simple process. I use multiple thin bearings, stacking them until the B/C gap and headspace are correct.

The same thing can be accomplished by stretching the yoke, but it is a more complex and involved process.

[Mk42gunner]

I see. Do you know what basis the instructor formed his opinion on?
I appreciate your response, and I do not dispute what you have said, I'm just trying to understand it as fully as possible.

Thank you !

I believe it was more of a "lesser number of parts means fewer problems when the idiots take the gun apart thing" than actually seeing one of the endshake bushings come apart and tie up the gun in a combat situation. It could have been a case of Murphy's Law avoidance too.

My instructor was a Korean War Marine BAR man that was the armorer for one of the big So Cal police departments. He had firm beliefs on keeping things simple for the frontline officers.

He also preached not to send any gun back out for service until it had been successfully test fired.

Robert

[Petrol & Powder]

I'll agree with the theory that stretching the yoke requires fewer parts and therefore less "stuff" to cause potential problems.

I prefer to stretch the yoke and made my own tool to accomplish that task. It's not something that I've had to perform on my own guns much but I've fixed a few for friends. One thing about excessive end shake is that it is self compounding. A little bit of excessive endshake will quickly become a lot of endshake if not addressed.

I have found that the Ruger Six series revolvers are almost immune to endshake problems. If a S&W is shot with excessive endshake it will deteriorate quickly if not fixed.

[Hannibal]

I think I understand the process now for the most part, but one detail eludes me. Is it possible to adjust the cylinder/barrel gap, and if so, by what means?
The particular revolver I am working on has .008" end shake. I plan to install .006" in shims. Should leave a .006" cylinder gap. Not horrible, but I wish it was about half that. Can this condition be adjusted/corrected?

Thank you for all the replies thus far.

[sargenv]

When my 610 developed the above mentioned cylinder meeting the barrel drag issue. I put in a .002" end shake bearing and it was good for another 20,000 rounds.. It's sort of a regular maintainance thing I check when I do my twice yearly tear down.. I've only had to use a couple of these bearings in the entire time I've had it.. (some 12 years and 120,000 rounds later).

[Petrol & Powder]

Expanman - correcting excessive endshake is the first step and in some ways more important than cylinder gap. Excessive endshake will cause the cylinder to hammer itself (and the yoke). After you correct the endshake issue you check the barrel/cylinder gap. If the gap is excessive the only way to properly decease the gap is to set the barrel back one thread and recut the forcing cone & breach face of the barrel.
I'd live with a little more barrel/cylinder gap long before I'd live with excessive endshake. One condition results in a slight loss of velocity while the other damages the gun.
All timing issues and barrel cylinder gap issues are corrected after endshake is corrected.

Hope that helps.

[Hannibal]

Expanman - correcting excessive endshake is the first step and in some ways more important than cylinder gap. Excessive endshake will cause the cylinder to hammer itself (and the yoke). After you correct the endshake issue you check the barrel/cylinder gap. If the gap is excessive the only way to properly decease the gap is to set the barrel back one thread and recut the forcing cone & breach face of the barrel.
I'd live with a little more barrel/cylinder gap long before I'd live with excessive endshake. One condition results in a slight loss of velocity while the other damages the gun.
All timing issues and barrel cylinder gap issues are corrected after endshake is corrected.

Hope that helps.

This is exactly what I wanted to know. Thanks VERY much.

[Petrol & Powder]

I think I understand the process now for the most part, but one detail eludes me. Is it possible to adjust the cylinder/barrel gap, and if so, by what means?
The particular revolver I am working on has .008" end shake. I plan to install .006" in shims. Should leave a .006" cylinder gap. Not horrible, but I wish it was about half that. Can this condition be adjusted/corrected?

Thank you for all the replies thus far.

I'm not sure you have a solid grasp on this. Adding shims or stretching the yoke will push the cylinder to the rear. Barrel/cylinder gap is the maximun amount of clearance between the breach face of the barrel and the front of the cylinder. Pushing the cylinder to the rear with shims will decrease the amount of endshake but by itself it will not change the cylinder gap. If you have .008" B/C gap when you start you will still have .008" after correcting the endshake but you'll have less endshake.
Fix the endshake first and deal with the B/C gap later if it is excessive.


Here's a good explanation: http://www.grantcunningham.com/blog_...0d2d5-127.html

[Hannibal]

Right, I follow what you are telling me. The shims are on order, once I have the endshake issue corrected, then I'll be able to evaluate the cylinder gap and decide if it's going to be an issue or not. Given the trouble of setting the barrel back, it's going to have to be a definite problem before I deal with it. I suspect it will be just fine.
Not sure what I was thinking when I put the .006" cylinder gap comment in there . . .

And thank you for helping me understand this. I appreciate it.

[MtGun44]

With a good forcing cone, an "excessive" cylinder gap can be no big deal, and
rectifying it can be a PITA. Most of the time you just live with it unless you have
a lathe and frame wrench, plus barrel facing tool with proper pilot.

[Petrol & Powder]

Mtngun44 is right on the money, setting a barrel back is not a casual job for the weekend gunsmith. I would be willing to bet that most of the time that job is undertaken because of other factors that require it. (front sight is not clocked properly, forcing cone and breach face were re-cut and the resulting B/C gap was too big or the barrel was replaced).
There's been a lot of discussion of the years about B/C gap and somewhere along the line it took on a little more significance than it probably should have. Yes, it is an important measurement when evaluating a revolver but it's not everything.
A B/C gap that is tight (narrow) will generally demonstrate higher velocities than a gun with a large B/C gap, with all other factors being equal. HOWEVER, there are other considerations. An excessively tight B/C gap can result in poor functioning, particularly with a dirty gun. I know former LE revolver armorers that would refuse to set B/C gaps at the low end of the allowable specifications for a duty gun. It is better to have a gun that always works than to have one that produces 10 fps more.
Obviously there are limits and you can go too far in either direction but it is one of those things where a little perspective is healthy.

[Hannibal]

Yes as I said earlier, I have no intentions of setting the barrel back unless it prooves to be a problem. And given the measurements I've taken, I'll be surprised if it isn't just fine. I'm not going down that road unless and until it proves necessary.

Thank you all again.

[tenx]

i have only used them on several rugers and smith & wessons but endshake bearings have worked really well for me. resist the tendancy to remove all endshake and have everything too tight. the hard stainless bearings seem to last forever with a drop of oil every now and then.