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Discussion Starter #1
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.




 

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No, that's not correct. I can see all kinds of lube and fouling buildup coming to those chambers. I'd send the pics to S&W and see what they say. They should make that good for you.
 

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Looks like their finish grinder had a major malfunction.
I worked at the old Saginaw steering gear plant years ago and we had something similar happen with one of their I.D. bearing grinders. For some reason it didn't drive deep enough into the part.
Looked almost identical to your issue, just on a much bigger part.

The cylinders are usually either milled or broached to get to the near diameter then a grinder drives down the throat to finish it out smooth. It Looks like the grinder stopped short on all of oyur cylinders.

S&W may end up with a recall on these. That could end up being a major issue.
contact the guys at S&W customer service and see if they have anything on this problem
in the books.
 

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Discussion Starter #4
DaveWW said:
No, that's not correct. I can see all kinds of lube and fouling buildup coming to those chambers. I'd send the pics to S&W and see what they say. They should make that good for you.
Thanks DaveWW. That is precisely why I started looking at the throats further. After the 200 rounds, I had significant leading of the forcing cone, even though I was shooting jacketed ammunition (UMC 38 spl 130gr metal cased).

Jim
 

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Discussion Starter #5
gearchecker said:
Looks like their finish grinder had a major malfunction.
I worked at the old Saginaw steering gear plant years ago and we had something similar happen with one of their I.D. bearing grinders. For some reason it didn't drive deep enough into the part.
Looked almost identical to your issue, just on a much bigger part.

The cylinders are usually either milled or broached to get to the near diameter then a grinder drives down the throat to finish it out smooth. It Looks like the grinder stopped short on all of oyur cylinders.

S&W may end up with a recall on these. That could end up being a major issue.
contact the guys at S&W customer service and see if they have anything on this problem
in the books.
Thank you gearchecker. I'm thinking a batch of cylinders missed the grinder process all together on the production line, based on the fact that the cylider face does not appear to be finished either, and that the shop has another one that looks exactly the same.

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.

Your comment on the recall thing 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 them (serial number range, test fire date, or what have you) so we can address it with Smith.

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

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Looks like they got one of them Slinkys stuck in there. You know, some folks are like Slinkys, makes yuh smile when yuh push 'em down the stairs. I think I could do a better job with my RCBS case mouth chamfering tool.
 

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That's gotta be a BEAR to clean. :?

The final polish step was obviously missed or someone wasn't paying attention to the condition of their cutters.

I've stood on the line where this is done and there are many different machines operated by many different people performing the same function. There were more than 80 CNC machining centers on the floor where cylinders and frames are made. Smith & Wesson was building 500 revolvers a day at that point.

Let them know. They'll take care of it.
 

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Discussion Starter #8
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
 

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You have nice photos and I agree with the others, the reamer they used was damaged or chipped as they should be nice and smooth not with a 500 micro finish like your cylinder.

On top of that I bet the throats are oversized that's why your forcing cone was loading up.

I'm sure Smith will give you a new cylinder. In a few weeks you will be happy with it then.
 

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Discussion Starter #10
Hi Magnum Nut,
I was actually thinking the opposite about the throat diameter. I am not sure if this is the proper way to measure, but using my digital calipers all 6 came out to .356. My guess was that the undersized throat coupled with the ridges were shaving the bullets as they left the cylinder. These shaving were then blown into the hot forcing cone where they melted and stuck. Again, that was just my guess as I am not sure my measurements were accurate.

Regarding the pictures, believe it or not, the camera is a pretty simple point and shoot (Canon PowerShot A630). The trick was actually reading the owners manual to learn about the settings and using a tripod!

Jim
 

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Unfortunately a dial caliper is not a reliable way to measure chamber throats. Consider picking up an inexpensive set of pin gages. I got mine on sale from Enco. I have measured all my revolvers with them. My .357 mags run from .357" to .359" (not on the same gun). The .357 guns are my 627PCs. They shoot extremely well. The gun with .359" also shoots pretty well, but most are .358". If yours is really .356", that could explain the poor finish: the cylinder somehow managed to miss final finish reaming of the throats. The logical thing is to send it to S&W and let them take care of it. The tinkerer in my would be tempted to ream the throats to .358" myself. Brownell's has the Manson reamers. It is easy enough, but not cheap.
 

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Discussion Starter #12
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
 

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Jim, I would call them and send it back, that is unacceptable.
 

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Discussion Starter #14
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
 
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