"Never ever, ever, ever, ever, ever, ever....."

[armorer951]

Caution, opinion follows:

If the boss on the extractor were impacting the breechface during heavy recoil we would be replacing extractors and frames, especially the aluminum frames. These frames would have a .010" deep cavity around the center pin hole in the breechface in no time.....from the extractor boss.

Almost all of the impact stress of the recoil force is imparted to the end of the yoke barrel by the cylinder. That explains the repeated peening at this location. The bosses on the extractor and the impact site on the frame from the boss remains "pristine" for the most part for years and years of firing, even on aluminum frame J series revolvers. The yoke barrels don't fair so well.

A visual indicator or "example" of what the cylinder is doing during recoil can be found in what can sometimes happen to the projectiles in unfired ammunition residing in the other chambers of the cylinder....particularly when heavy loads are fired in lightweight revolvers. These unfired projectiles can literally "jump forward" out of the shell casing as the revolver moves backward.
The exact same thing happens to the cylinder under recoil as it moves forward, (or actually tries to stay still) resulting in the bearing surface of the bottom of the cylinder yoke cavity violently striking the end of the yoke barrel, which is moving backward with the frame.


Carter

 

[steelslaver]

Thar surface area on the end of the yoke is smaller than the surface are on the center of the yoke. The end of the yoke tube is only about 3/8" OD and less than 1/16 thick around its end. 3/8 is .375 x 3.14=1.1775. 1.1775x.0736 sq in of surface on end of yoke tube. If the center of the ratchet is about 5/16" that is .3125 .3125/2=.15625 .15625x.15625= .0244 and that times .314=.0766 so not much difference in surface area between end of yoke tube and center of ratchet.

The unfired cases move with the cylinder in recoil, the fired case is expanded tight momentarily while under the pressure of ignition and stock to the chamber walls and the cylinder would move back with it as the bullet is expelled. The bullets in those unfired cases try to remain at rest when the cylinder is violently accelerated to the rear pressing their rims of their cases along for the ride. Then when the cylinder stops by slamming into recoil shield the cases keep on going until they too strike it.

There is not much damage to end of the ratchet button because it does not have enough room to accelerate much before meeting the recoil shield, but same is true of yoke tube.

I bet if I set up a cylinder with a lot of end shake and a long firing pin the center of the ratchet would get hammered faster than the end of the yoke.

Hold a shotgun tight to your shoulder and touch off a 3" magnum. Then hold it an inch away from you shoulder and fire another. If you still do not understand the concept hold it 6" off and fire a third

Just the fact that revolvers can put up with thousands of rounds of magnums is kind of amazing when you think about every thing that is happening no matter what hits what first, second or third.

 

[rosewood]

I am betting those shims coming a part is fake news! Most likely internet fodder.

Lots of things use shims to take up play and come with them from the factory. Rear end gears in an axle come to mind.

It is so much harder to convince someone something they believe to be true is wrong or there is a better solution than they think they already know, than it is to teach someone something to start with. If you learn it one way, hard to believe there is a better way.

I myself always look at something and think, I bet I can come up with a better way. But I am an engineer, that is the way I was born.

Rosewood

 

[armorer951]

I'm going to have to defer to your background, training and great experience on this one. I'm certainly no expert, by any means.


In the case of my aluminum frame 442, the extractor boss is tiny compared to the cross section at the end of the yoke barrel. Damage to the aluminum breechface caused by pressure from the center pin during opening and closing is worse than that caused by the extractor boss. Even the finish under the boss's contact site on the breech is mostly still intact.

To me, this is just another visual confirmation of where the recoil stresses are actually distributed. The cylinder is not slamming against the recoil shield, it's actually impacting the end of the yoke barrel. The fact that we're buying shims or stretching the yoke bbl to deal with yoke damage also confirms this.

As I said above, I'm mostly clueless and definitely not an engineer.

Carter



boss:



Extractor boss damage to breech.....zero:

 

[steelslaver]

The center section on that is certainly a lot smaller than N of K frames. Nut so is the cylinder. I just find it had to believe that the cylinder just sets there not moving will the powder contained in a case explodes pushes a bullet out of it. The fact that a yoke tube and the mating surface in the cylinder wears wears .002 after a bunch of rotation does not surprize me

But none of the pieces are going all that fast when they come together. There is a super slow mo of a revolver beling fired and you can still have a hard time seeing any cylinder movement. But when viewed at 64,000fps around the 30 second mark it sure appears the cylinder goes back
Unfortunately he only shows the muzzle at 224,000fps
[ame]https://www.youtube.com/watch?v=QSlLZeWLy3s[/ame]

on this one which is only a 22 you can see the cylinder bounce forward way after the fact at around 35 seconds

[ame]https://www.youtube.com/watch?v=RynFnKzt9JM[/ame]

 

[WR Moore]

Thar surface area on the end of the yoke is smaller than the surface are on the center of the yoke. The end of the yoke tube is only about 3/8" OD and less than 1/16 thick around its end. 3/8 is .375 x 3.14=1.1775. 1.1775x.0736 sq in of surface on end of yoke tube. If the center of the ratchet is about 5/16" that is .3125 .3125/2=.15625 .15625x.15625= .0244 and that times .314=.0766 so not much difference in surface area between end of yoke tube and center of ratchet.

Ah, my math is a bit different. I measured the parts of a 64-5 and got a yoke barrel OD of 0.382 in, ID 0.312 in. The button in the ratchet is 0.285 in. Running the math, if the yoke barrel was solid, the area would be 0.1146 sq in. The area of the ID is 0.0764 sq in. OD-ID is 0.1146-0.0764= 0.0382 sq in. So, the surface area of the yoke is 0.0382 sq in.

The button in the ratchet center is 0.285 in . Doing the math for the area it's 0.0638 sq in. So, the button in the ratchet has not quite twice the area of the end of the yoke barrel.

 

[steelslaver]

Ah, my math is a bit different. I measured the parts of a 64-5 and got a yoke barrel OD of 0.382 in, ID 0.312 in. The button in the ratchet is 0.285 in. Running the math, if the yoke barrel was solid, the area would be 0.1146 sq in. The area of the ID is 0.0764 sq in. OD-ID is 0.1146-0.0764= 0.0382 sq in. So, the surface area of the yoke is 0.0382 sq in.

The button in the ratchet center is 0.285 in . Doing the math for the area it's 0.0638 sq in. So, the button in the ratchet has not quite twice the area of the end of the yoke barrel.

Thanks you. I am setting in WA state away from my desk with no access to my calipers or screw driver to tear the gun I have with me apart. I was making an educate guesses. Plus, I must have messed up a bit on the math somewhere. Really one needs to subtract the center pin, but that would not be much.

But, all that aside I do believe most of us doubt that a shim will break or cause trouble. Lots of little pieces in a revolver are getting a pretty rough ride during recoil.

 

[chief38]

Now let's look at the alternative method which is stretching the yoke with the tool. When metal is worked or stretched I have to believe it is also softened & weakened a bit. Under recoil I would think that eventually the end shake would return. The more times the yoke was stretched the faster end shake would become a problem again.

Is there a fault in my thinking?

 

[steelslaver]

When you cold work steel by doing things like run a roller on it or hammer it you actually work harden it, not soften it. Work hardening actually makes it more brittle. Basically that is what happens when you fold a piece back and forth until it cracks and breaks. I have cut a lot of tubing and even with a sharp wheel a lot of metal gets displaced making it thinner and thinner verses actually cutting it. Not only will the end ID will be considerably under sized but the OD will be slightly larger when the "cut" is finished. Displacing enough of the yoke tube with a dull wheel to make it grow a.001 or 2 wouldn't cause much. Plus, you could use 2 or more spots. At any rate it would make the tube slightly weaker but not a lot. I would think slamming on the end of the tube with the cylinder would be more apt to deform the end more than the stretched part.

Why doesn't anyone think that the hand turning the cylinder pressed against the tube wouldn't slowly wear the end of the tube and bottom of the hole. If you were to mic the end of a tube and then fire a bunch of hot rounds in the gun if the endshake comes from the cylinder being slammed on the end of the tube the should get thicker as metal is being displaced.

If you take a piece of tube or pipe and start hitting the end of it, the end will begin to mushroom. I know that for a fact.

I like the shims myself because they provide really smooth surface that would cause almost no drag. The end of a tube is pretty soft by comparison. It would slowly displace and deform well before the shim would

I am no more worried about a shim than the yoke screw, button, cylinder stop, stop notch, gas ring, pivot pins for DA sear, hand, the stirrup etc. The rivet and the hammer nose also takes a lot of wacks, first on striking the firing pin then when the case and primer slams back on it before you can release the trigger. Maybe Ed McGivern and Jerry Miculek excepted

 

[chief38]

When you cold work steel by doing things like run a roller on it or hammer it you actually work harden it, not soften it. Work hardening actually makes it more brittle. Basically that is what happens when you fold a piece back and forth until it cracks and breaks. I have cut a lot of tubing and even with a sharp wheel a lot of metal gets displaced making it thinner and thinner verses actually cutting it. Not only will the end ID will be considerably under sized but the OD will be slightly larger when the "cut" is finished. Displacing enough of the yoke tube with a dull wheel to make it grow a.001 or 2 wouldn't cause much. Plus, you could use 2 or more spots. At any rate it would make the tube slightly weaker but not a lot. I would think slamming on the end of the tube with the cylinder would be more apt to deform the end more than the stretched part.

Why doesn't anyone think that the hand turning the cylinder pressed against the tube wouldn't slowly wear the end of the tube and bottom of the hole. If you were to mic the end of a tube and then fire a bunch of hot rounds in the gun if the endshake comes from the cylinder being slammed on the end of the tube the should get thicker as metal is being displaced.

If you take a piece of tube or pipe and start hitting the end of it, the end will begin to mushroom. I know that for a fact.

I like the shims myself because they provide really smooth surface that would cause almost no drag. The end of a tube is pretty soft by comparison. It would slowly displace and deform well before the shim would

I am no more worried about a shim than the yoke screw, button, cylinder stop, stop notch, gas ring, pivot pins for DA sear, hand, the stirrup etc. The rivet and the hammer nose also takes a lot of wacks, first on striking the firing pin then when the case and primer slams back on it before you can release the trigger. Maybe Ed McGivern and Jerry Miculek excepted

Thanks for the clarification on what happens to metal when worked - I did not realize that it actually hardened - but I guess that is why hammer forging is so good. I always enjoy reading your posts and have learned things from them! I will never be too old to learn!

 

[rosewood]

The rivet and the hammer nose also takes a lot of wacks, first on striking the firing pin then when the case and primer slams back on it before you can release the trigger. Maybe Ed McGivern and Jerry Miculek excepted

This made me laugh.

 

[llowry61]

People who become aggressive when their opinions are questioned are not my kind of people.

 

[RetCapt]

One of the more interesting threads I have read on the Gunsmithing Forum.

I have a Ron Power shim in one of my revolvers. One shim did it so there is no end shake that I can detect. In fact, at the outset there was a question in my mind whether the revolver would still close with the shim in, it was that close.

Due to various circumstances I have only minimally shot that revolver in the intervening years. I was going on the assumption that all would be well though, given Ron Power's stellar (legendary really) reputation.

The several experiences related here, chief38 being most relevant to me, have confirmed my assumption has been correct. Now I just need to generate more shooting time, and prioritize taking that revolver out. We have a lot of history together, so I wanted to confirm that it is up to spec.

Thank you to a number of you for your experiences.

 

[CH4]

Shims work for Jerry Kuhnhausen, and they work for me. I used them on a 2.5" 66-1 and they worked as designed.

 

[WR Moore]

I had some thoughts about the back and forth motion of the cylinder.

At hammer impact, the cylinder may move forward, when the primer ignites, it moves backward to the breech face. As the case pressurizes, the case will move back against the breech face as the case begins to swell/obturate. The cylinder move back against the breech face might/might not happen until the bullet enters the throat of the chamber.

 

[rosewood]

And whether the case grips the cylinder on it's rearward movement may determine on whether the cylinder moves at that point. Low pressure cartridges sometimes do not grip the cylinder/chamber whereas the higher pressures ones likely always do.

Rosewood