Gas ring yoke vs cylinder

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Ron In MD

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Is there a preference?
Why?
Is one better than the other?

Since I am a visual guy, can someone post pictures, one showing the location of the gas ring on the yoke and a picture of the gas ring on the cylinder?

I am having a hard time visualizing what they look like.

The M10-7 that I am looking at has:
4” HB
Round Butt
SN AVN xxxx (1987)

Thanks.
 
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double-dipper said:
Well if you're talking about the K frame 19's or 66's read this.

The Smith & Wesson L-Frame Story - RevolverGuy.Com
Click to expand...

Good article, the part about stainless steel’s properties is not quite accurate.

The author writes: “ Stainless conducts heat differently, and has a tendency to heat and expand quickly, which could wreak havoc on guns with close tolerances.”

Stainless has roughly 1/3 the thermal conductivity of carbon steel. It is slower to propagate thermal energy, but does expand a bit more than carbon steel in the temps experienced by a handgun.


A more accurate statement would be that while stainless heats and expands more slowly, overall dimensional growth is greater than with a similar carbon steel part.
 
double-dipper said:
Well if you're talking about the K frame 19's or 66's read this.

The Smith & Wesson L-Frame Story - RevolverGuy.Com
Click to expand...

Lot of good information here with many details I’ve never read before. Never knew Roy Jinks was behind the full lug barrel appearance. Nice to see the 620 get some recognition. There’s a typo in there about its barrel length though. It’s a 4” gun, not 5”, and one rather unappreciated gun.
 
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double-dipper said:
Well if you're talking about the K frame 19's or 66's read this.

The Smith & Wesson L-Frame Story - RevolverGuy.Com
Click to expand...

EXCELLENT!

Actually I am looking at a M10-7. Except this particular one has a 4” HB.
It also has a round butt.
Did S&W make 4” HB round butt M10-7?
Would the yoke mounted gas ring make a difference to anyone?
The AVN serial number dates it to 1987.

The attached picture shows the area of concern. To my untrained and diminishing eye sight, I can’t tell if the gas ring is yoke or cylinder mounted.

Comparing pictures it appears that the gas ring is on the yoke, as there seems to be is a slightly more amount of space between the frame and cylinder gas ring, again to my eyes, as compared to my M65-5.



Thank you.
 

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Does it make a difference? YES! I once had to service a group of model 10's that belonged to a college LE training course. They had the yoke mounted gas ring and the cylinders had become very hard to rotate.

The problem was lead/carbon/powder residue buildup inside the front of the cylinder yoke bores. It was so hard I had to chuck the cylinders in a lathe and machine it out.

Possibly if one removed the cylinder from the frame & yoke and cleaned that area after each range trip, it might not be a problem. However, the extractor rod interferes with a thorough cleaning. Taking the cylinder apart isn't suggested.
 
Thanks for that....

double-dipper said:
Well if you're talking about the K frame 19's or 66's read this.

The Smith & Wesson L-Frame Story - RevolverGuy.Com
Click to expand...

...just the last few days I was pondering mystery I've been wondering about for years. Thanks for the illustration.

My brilliant idea: Instead of machining a flat to clear a circular object, why didn't they machine an arc to match the radius of the gas ring? That would leave a lot more metal in place it seems.:confused:
 
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rwsmith said:
...just the last few days I was pondering mystery I've been wondering about for years. Thanks for the illustration.

My brilliant idea: Instead of machining a flat to clear a circular object, why didn't they machine an arc to match the radius of the gas ring? That would leave a lot more metal in place it seems.:confused:
Click to expand...

I would guess that the hoop strength/hoop stress is largely dictated by minimum thickness and not total material.
 
Here are two additional pictures of the gas ring on the M10-7 that I am looking to buy.

Again, I am not sure of what I am looking at.
It does appear that the gas ring is attached to the cylinder and not the yoke.

Am I correct?

Thanks.
 

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Ron In MD said:
Here are two additional pictures of the gas ring on the M10-7 that I am looking to buy.

Again, I am not sure of what I am looking at.
It does appear that the gas ring is attached to the cylinder and not the yoke.

Am I correct?

Thanks.
Click to expand...
You're correct, your gas ring is attached to the cylinder.

That article from the Revolver Guy was fantastic, cleared up a lot about the K frame forcing cone issues, and I'd never gotten a clear idea about the difference in the two types of gas ring, so thanks to snw19_357 for those pictures.

After reading this, I had to go examine my M19-3 (1974 vintage) and M66-1(1980 vintage) to take close looks at the forcing cones and gas rings. Both my guns have the gas ring as part of the cylinder, but my M19 has the original type undercut on the forcing cone, where the M66 has the more extensive cut. When the cylinders of each are closed, there is a tighter fit of the gas ring against the cone on my M19, and there's more "daylight" between the ring and cone on my M66. I've been carrying the M66-1 (RB, 2-1/2" barrel) as an EDC for a while, and have it loaded with 158 grain JHP's, but something less than full power; they're in the 1200 fps range, so I hope that will be enough, as I practice with what I load with for carry.
 
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Gas rings, yoke mount vs cylinder

Here's a strange one. I picked up a model 66, no dash with a S/N that puts it in 1974 vintage. The gun has a SS sight, pinned barrel and recessed cylinder which matched the frame contour perfectly. It does not have a yoke mounted gas ring. The gas ring is on the cylinder. I picked up from a parts guy a SS yoke with the gas seal and matching, recessed cylinder. It fits my gun but the profile of the yoke does not quite match the frame. It has material relieved below the extractor pin showing more of the frame. I read an article that S&W went through a period where they started resorting back to the cylinder gas ring before the -1's where officially launched. Anyone have any ideas? Do I have some kind of hybrid?
 
By your description of a, "SS sight", I will guess your M66's serial number starts with a 2K, 4K or low 7K; which is before the gas ring was moved to the yoke in late 1975.
The gas ring was moved to the yoke right around the same time that the stainless sights were replaced with the red ramp and blackened rear sight.

Yes, there are 2.5" no dash Model 66s in the 15K and 17K range and square butt model 66's in the 35K range that have the improved gas ring on the cylinder but are not marked -1 yet.
 
Interestingly enough I noticed that on my new J frames the gas ring is on the yoke, at least on the new alloy ones I have. A 431 and a 642. No problems so far.

As to an arched cut instead of a flat.

First it could not actually be much of an arch as the yoke and cylinder move in from the side so they would hit a the downward portion on the left side. Next because the forcing cone is circular the thinnest part ir directly below its center and a flat gets thicker fast as it moves laterally from bore center line. Next if you actually did manage to make an arch work it would collect move blast gasses and focus them in on that thin spot, where a flat lets them escape out the sides.
 
Thanks SNW 19 357,

Very useful info. I think I’ll keep my 66 set up with the cylinder mount gas ring as I got it. They performed better anyway.
 
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