Gas Ring Moved from Yoke to Cylinder

Dodge City · Dec 13, 2013

Can someone explain this to me? I have a model 19-3 and a 19-4. According to the SCOSW, the 19-4 (1977) had the gas ring moved from the yoke to the cylinder. I took the cylinders off both guns, removed the ejector rods and ejector (star) from both cylinders. I saw no difference between the two. The yokes and cylinders looked the same to me. What am I missing? I look forward to an explanation. Thanks.

Gun 4 Fun · Dec 14, 2013

Welcome to the forum.

Unless your 19-4 was right at the very beginning of the -4 run, they're different, but you just missed seeing it. If your -4 was right at the very beginning of the -4 run, it's possible that they are both still on the yoke even though the -4 engineering change was for the relocation of the gas ring. Never say never since S&W didn't waste anything, including frames or any other parts.

The gas ring is just that, a little steel ring that was originally mounted/part of the yoke right up against the arm of the yoke, but was later changed to be recessed into the face of the cylinder. Take your guns out and open the cylinders, then look down at them side by side from above- right in front of the cylinder. There will be a difference that can be seen when comparing them that way. The -4 should look slightly longer on the small protrusion in front of the cylinder than the -3 gun should look.

I know there's a thread here somewhere that shows the difference in pictures, but have no idea where it's at now.

Dodge City · Dec 14, 2013

Both look the same. I wanted to do a search about this but I can't find a search button. All my revolvers are early ones except the 19-4. I need to see a picture. The reason I asked about this was that I just bought a replacement cylinder for my model 15-3 because I don't like the finish on the one on the gun. It has a cloudy looking blue. The prior owner probably used something he shouldn't have when cleaning. It was advertised as a like new K frame cylinder that will fit a model 10, 14, 15. I ordered it without the ejector rod, star & yoke. It's got the small ring attached to the front of the cylinder as the one that's on the gun now. I just want to make sure I'm not going to screw anything up with this gas ring.

Gun 4 Fun · Dec 14, 2013

I should have told you this first- if the gas ring is in the wrong location, the new cylinder will not fit your gun.
Here are a couple pics showing the difference.

The one on the left is from my 15-3. You can see the large ring in the face of the cylinder that is not there on the cylinder from my 17-3 on the right-

Take a look at these two yokes. The one on the left is from my 17-3, the one on the right from my 15-3. You can see the large gas ring up next to the arm of the yoke on the yoke on the left-

murphydog · Dec 14, 2013

"I wanted to do a search about this but I can't find a search button."

Have a look at the top of the home page, just under and to the right of the "Forum" and about where the K-32 is pointing. The "Search Site/Google" function always seems to work better than the other methods.

My recollection is the yoke mounted gas ring worked better in blocking crud from entering the open center of the cylinder, and the cylinder mounted one was only used for a brief period of time.

66snub · Dec 14, 2013

I've wondered about this as well. Thanks for the info, it was very helpful.

Flint Ridge · Dec 14, 2013

By chance is there an "R" on the cylinder face? Long shot, but didn't a slim number get sent back to the factory by owners with problems and replace these parts?

I have 2 66's that are no dash, prior to change. One an 8K serial number, just as it should be. The other a 4K serial with the gas ring moved etc. Back of cylinder face has a small "R" easily visible outside the ejector star.

Dodge City · Dec 14, 2013

This is weird. My 15-3 has the cylinder the same as yours. The yoke, however, looks like the 17-3 but has been machined down to look like the one on your 15-3. Mine has small cutouts like your but the "stop" has been smoothed and relocated to the rear. The cylinder does not come to the stop. I think I should order a new yoke. I get these parts from MagnumMark on GB. There is no "R" anywhere.

Neumann · Dec 14, 2013

The best arrangement is a gas ring on the cylinder. It consists of a tightly fitted sleeve, pressed into the cylinder, with an extension past the gap to deflect hot gases so they don't foul the shaft of the cylinder.

That arrangement was changed on a later revision of the K-22/M-17 to a separate ring fitted to the yoke. That's how my post-1980 S&W revolvers work too. This is not nearly as effective at keeping the shaft clean.

I'm not familiar with the evolution of the M-19, but a change TO a gas ring on the cylinder would be an improvement, not a cost reduction.

Dodge City · Dec 14, 2013

Gun 4 Fun,, You see any reason not to keep the existing yolk on the 15-3? The distance between the cylinder and the forcing cone is right on the money.

snw19_357 · Dec 14, 2013

Dodge City said:
Can someone explain this to me? I have a model 19-3 and a 19-4. According to the SCOSW, the 19-4 (1977) had the gas ring moved from the yoke to the cylinder...The yokes and cylinders looked the same to me. What am I missing? I look forward to an explanation. Thanks.

That is correct, the gas ring was moved from the yoke to the cylinder in 1977 resulting in the -4 change.
What isn't mentioned, and for some reason didn't get a dash number, is that in 1974 the gas ring was moved from the cylinder to the yoke, about the 6K5's for RB and 7K2's for SB.

The gas ring on K-frames was originally on the cylinder so 19-3's made between 1967 and 1974 will have it on the cylinder.

Gun 4 Fun · Dec 14, 2013

Dodge City said:
Gun 4 Fun,, You see any reason not to keep the existing yolk on the 15-3? The distance between the cylinder and the forcing cone is right on the money.

If it fits correctly and everything works as it should, I wouldn't bother changing it.

The gas ring on the cylinder is a far better set up fopr keeping the yoke barrel clean and the gun running more smoothly for a longer period of time.

Gun 4 Fun · Dec 14, 2013

murphydog said:
My recollection is the yoke mounted gas ring worked better in blocking crud from entering the open center of the cylinder, and the cylinder mounted one was only used for a brief period of time.

It was just the opposite, with the cylinder mounted ring being the std except as noted above when it was moved to the yoke for appr. 4 years, then moved back to the cylinder. The cylinder mounted ring keeps the gas and fouling out far better.

Dodge City · Dec 14, 2013

snw19_357 said:
That is correct, the gas ring was moved from the yoke to the cylinder in 1977 resulting in the -4 change.
What isn't mentioned, and for some reason didn't get a dash number, is that in 1974 the gas ring was moved from the cylinder to the yoke, about the 6K5's for RB and 7K2's for SB.

The gas ring on K-frames was originally on the cylinder so 19-3's made between 1967 and 1974 will have it on the cylinder.

I have 4 model 19's. 19-3 2 1/2 blue snub RB, 19-3 4" blue SB, 19-3 6" blue SB & 19-4 4" Nickel SB. All are gas ring in the cylinder. Only the -4 was made in 1978. The other -3s are in your date range. That's explains the the difference in the SCOSW book. Thank You

Dodge City · Dec 14, 2013

Gun 4 Fun said:
If it fits correctly and everything works as it should, I wouldn't bother changing it.

The gas ring on the cylinder is a far better set up fopr keeping the yoke barrel clean and the gun running more smoothly for a longer period of time.

Thank you, I'll keep it.

Dodge City · Dec 14, 2013

I would like to thank everybody for their input. I've learned a great deal about this subject. I'm grateful for having this outlet for knowledge and for people that are willing to help. Thanks again. , Mark

murphydog · Dec 14, 2013

Gun 4 Fun said:
It was just the opposite, with the cylinder mounted ring being the std except as noted above when it was moved to the yoke for appr. 4 years, then moved back to the cylinder. The cylinder mounted ring keeps the gas and fouling out far better.

Thanks for clarifying this...now all I have to do is keep it straight in my head!

DR505 · Dec 14, 2013

I think this is good info on gas rings. I'm making this comment so in the future I can just search my own posts and find the thread!

BJoe · Dec 14, 2013

Got to remember that S&W NEVER threw anything away so model changes actually happen when parts run out, not necessarily by year, or dash number.

Vulcan Bob · Dec 15, 2013

If memory serves me right my 19-3 with the gas ring on the yoke would start to foul the cylinder pin making the cylinder hard to rotate after one hundred rounds or so. Other than being a pain having to disassemble the cylinder for cleaning I don't find it to be a problem. However I do prefer the gas ring on the cylinder but its not a deal breaker either way.

Gas Ring Moved from Yoke to Cylinder

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