Possible cylinder throat issue

[InMotion]

Hello all. I picked up a brand new 686-6 last week. Put 200 rounds through it over the weekend. Came home and started cleaning and noticed something odd with the cylinder throats. This is not my first revolver, but it is the first time I have seen anything like this.

There are what appear to be lathe or some other machining marks in all 6 throats. It is my understanding that the throats should be somewhat smooth. Mine are not. The chamber areas are though. I went back to the shop I purchased from and took a look at 3 other Smiths they had there. They had a 620, a 627, and a 3" 686+. The throats of the 620 and 627 were nice and smooth, but the 686+ had the same marks as mine.

Can someone else with a recent production 686 check their throats to see if they look like mine? Is this something I should be concerned about? Just trying to figure out if this warrants getting sent back to S&W or if this is the new way they are reaming cylinders.

 

[Aussie44]

That's not normal,Send it back to Smith.Even the face of your cylinder has the machine marks.


Ken

 

[Milton]

The last cylinder I saw that in was a Ruger .357 that had not been finished.As has been said call or send it back to Smith.

 

[5906fan]

the chamber in the lower right is realy rough at the bottom, I'd send it back.

 

[InMotion]

Thanks for the replies thus far guys. It is odd that the gun shop has another one that looks exactly the same. I am wondering if a batch of cylinders didn't make it to the finishing stage of the production line. This also destroys my faith in the "final inspection" process. One would have hoped they at least checked the throat diameter and would have noticed the marks at that time.

I sent the same pictures to S&W yesterday but have yet to hear back from them.

 

[duckloads]

I had tool "chatter" marks in the tappered area in the cylinder throats of my 625-9 MG. S&W replaced the cylinder free of charge. It took a couple of months, but the gun shot better than new.

 

[snowman]

I checked my 686-6 after seeing your pictures. I had difficulty seeing the throats clearly even with a magnifying glass, but they appeared to have a slight tool mark here and there, but not nearly as pronounced as yours.

Andy

 

[InMotion]

I checked my 686-6 after seeing your pictures. I had difficulty seeing the throats clearly even with a magnifying glass, but they appeared to have a slight tool mark here and there, but not nearly as pronounced as yours.

Andy

Thanks Andy. It helps if you use an LED flashlight or hold it close to a florescent light bulb. You will then be able to see them really well (if present).

That is mainly what I was looking for……..to see if the marks appear on other owners 686s as well. If others have the same thing, we may be able to find a common denominator between then (serial number range or what have you) so we can address it with Smith. Perhaps I should have posted this in the main forum?

Jim

 

[InMotion]

I had tool "chatter" marks in the tappered area in the cylinder throats of my 625-9 MG. S&W replaced the cylinder free of charge. It took a couple of months, but the gun shot better than new.

Wow, I hope that won't be the case with mine. I am assuming that the entire cylinder was replaced on yours because removing the "chatter" marks would have opened up the throat diameter to outside of spec?

Jim

 

[snowman]

Jim,

I examined mine again under much better light, and they're OK. What I thought were tool marks were apparently an illusion.

Something else which hasn't been mentioned is the chamfered mouths on your cylinder. I don't think that is right either. I would definitely send your gun back.

Hope things turn out as they should.
Andy

 

[InMotion]

Smith has replied that they would like it sent back to them. I have returned it to the gun shop and it is on its way back. I will let you all know what the outcome is.

Jim

 

[InMotion]

Update. Received the revolver back from Smith today. The paper work states that they replaced the cylinder. The cylinder is definitely a different one. Ironically though this new cylinder has the same marks in the throats! I suppose S&W deems this to be normal and or acceptable.

A bit more disappointing is the fact that there is now side to side cylinder play (not end shake). The cylinder had absolutely ZERO play in any direction when I sent it to them. The play is almost a "wobble" where the cylinder fits on the crane tube.

To illustrate what I am trying to say, take a look at this picture:

Imagine that the red area was a smaller diameter then the green area. You can then picture in your mind how the cylinder "wobbles" on the shaft. This wobble occurs during full lock up.

I really don't want to send this thing back again. Is having some play like this acceptable? I have not had the chance to measure the actual play yet, but would guess it to be around .005.

Jim

 

[Gun 4 Fun]

There's always a .001"-.002" thousanths play to allow the cylinder to rotate freely, but .005" is pushing it. The play is usually spread out over both bearing surfaces on the yoke barrel though. If the cylinder is doing the "wobble" during full lock up though, I would send it back again. That kind of crap is inexcusable to me. There should be almost no detecable movement at full lock up, other then very minor sideplay. Sideplay is actually rotational movement on the cylinder stop. It is different from what you are describing. It sounds like the yoke bearing surfaces of the crane are now too small in diameter for the new cylinder's yoke tunnel, and is allowing the movement you describe.

 

[InMotion]

Thanks Gun 4 Fun. That is exactly what it seems to me as well. Under full lock up, I think the cylinder stop is nice and tight which holds the rear of the cylinder still, but the front of the cylinder can still move on the yoke barrel, giving the impression of a wobble (there is no rotational play on the cylinder stop).

I will check the side to side play with the cylinder swung open when I get home from work to see if the back side of the cylinder moves as well. This should tell for sure if the entire length of the yoke barrel is undersize or just the front.

Jim

 

[Twist]

The yoke will need to be internally expanded or replaced, I have seen one that had been expanded and it worked just fine, how it was done ... to be truthful - I am unsure.

 

[InMotion]

Okay, I think I was a bit over zealous with my "guestimate" of the play on the yoke barrel. Here is what I did:

I measured the thickness of a piece of scotch tape. This came out to be .002. I then wrapped 1 layer over the entire circumference of both ends (bearing surfaces) of the yoke barrel. The cylinder would NOT slide on. This tells me that the total "wobble" play (full left to full right) is less then .004.

I then wrapped half of the circumference with 1 layer of the tape. The cylinder would now slide on the yoke barrel, but just barely. So it would seem that my total wobble is about .002, which should equate to the yoke barrel outer diameter being about .002 smaller then the cylinder inner diameter.

For some reason moving the cylinder around on the yoke barrel "feels" like it is moving a lot more then it actually is. I think I am in the clear.

Jim

 

[Gun 4 Fun]

Jim,
If you have .001" at the rear bearing surface, and .001" at the front bearing surface, that would equate to a total of .002" and would be detectable, but seem much worse than it is, especially when you are already concerned about it.

You need some play to allow the cylinder to rotate when the gun gets heated up from firing, and also to allow the cylinder to turn when it becomes powder fouled. I know the gas ring is supposed to help prevent this, but fouling always gets down in between the cylinder and yoke, which is one reason they are made by the factory to be so easy to disassemble and clean.

I think you are probably fine, but if it keeps nagging at you, have them check it.