Let's talk 1970s K frame magnums

I know what you're thinking "oh no not another K frame forcing cone thread" but yes I'm going there one more time. I just watched a video on the K frame forcing cone issue and while the guy made some good points I still think it's not nearly as big a deal as it's made out to be.

Apparently moving the gas ring from the front of the cylinder to the yoke required more metal to be taken off the forcing cone and this was during the 70s. Model 19-4s and no dash 66s had the yoke mounted gas ring. Then when they put the gas ring back on the cylinder they didn't go back to the original spec. I made a comment on the video and theres a whole other side to this people don't know about.

The Ruger Security Six (and its variants) had a full forcing cone for most of its production life. It also didn't have a gas ring on the cylinder, it was part of the yoke (crane in Ruger terminology). That allowed Ruger to have a full forcing cone in a k frame sized revolver. There's obviously some difference between the two considering it required S&W to take off more metal from the forcing cone but in theory it should've allowed them to take less metal off than before.

Sometime around 1984-1985 Ruger moved the gas ring to the front of the cylinder which required the same relief cut as the K frames. What's crazy is you never hear of an issue with the Rugers that have the flat spot. The SP101 also had the flat spot for most of its life and again you never hear of an issue. Sometime in the last 10 years or so they were able to have a full forcing cone but I've seen many SP101s with the flat spot. Perhaps it's a difference in metallurgy, or because the Rugers we're designed for 357 in the first place, maybe their design allowed them to leave more metal than S&W, I don't know. I just find it odd that there are so many complaints about vintage K frames and the forcing cone yet you never hear of an issue with Ruger. I have a couple of the late model Six series revolvers with the relief cut, one has seen a good amount of full power 357 and shows no sign of developing an issue.

I believe the K frame forcing cone issue was a perfect storm of things. The gas ring change requiring more metal be taken off, police starting to practice and qualify with magnum ammo rather than just carrying it, along with the hot 125 and 110 grain ammo coming into vogue around this time. I'm not going to say it was only lighter bullets that did it but most of the cracked forcing cones seem to have been from steady use of 125 and 110 grain flamethrowers.

We have to keep in mind that SAAMI lowered the specs for 357 in the 1990s so today's 357 isn't what it was in the 70s and 80s. The reloading world really puts things into perspective also. When the forcing cones were thinned further is around the same time as Speer #8, none of today's manuals are even close to the max loads that were in the 70s and 80s manuals. I have 38+p data from 1992 that today's data doesn't even touch. A lot of police even carried hand loads back then, some departments had reloading benches and would load their own practice ammo. Loads that were normal and considered safe back then are known to be over pressure today. I have to assume the ammo companies probably loaded hotter back then simply because pressure testing back then wasn't as precise as it is today. I'm sure the ammo itself was a big contributor to this, especially with lighter bullets. I also have to think that powder selection may have played a role as well. Some powders burn hotter than others. Feed a vintage K frame nothing but 158 grain loads using HS6 and it'll probably last a life time, switch to 125s and Lil Gun and it'll probably wreck you're forcing cone in short order. Think about Speer #8, no one will even dare to quote loads from that particular manual because they're that dangerous. How many K frames were subjected to loads from that manual? Even an N frame or GP100 wouldn't stand up to long term abuse from the loads in Speer #8.


I have to believe with modern ammo and bullets over 125 grain that a vintage K frame 357 would hold up just fine. Especially if you're a reloader and you're using 158s below max loads. If they were truly these delicate butterfly's that they're made out to be I highly doubt there would still be thousands if not millions of them in the wild today and they certainly wouldn't be as sought after as they are. I'm not saying it didn't or doesn't happen but I don't think the issue is as big as it's made out to be. I've only ever seen it in pictures. Yes the k frames were intended for practice with 38 and carry 357, but we now have J frames and really small 357s with very thin forcing cones that hold up just fine. We also have the Golden Saber and Gold Dot Short Barrel that are far from full power yet still above 38+p. There's also the Buffalo Bore and Underwood 38+p loads that are about equal to the 38/44 loads. I dont think it's necessary to baby a vintage K frame with the lightest target loads possible just because of the forcing cone. I think they can handle modern 158s, the lighter defense loads and the 38/44 type loads just fine.


Maybe I'm missing something here but I just don't think that it's the widespread issue that it's made it out to be. I wouldn't shoot nothing but 125s and max charges of Lil Gun or H110 but I wouldn't do that with a 686 either. Abuse can ruin any gun, take care of it and it'll take care of you.

Well said, sir!

bobsguns said:

Well said, sir!

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Thanks, I just had to get my thoughts on the situation out there. I believed the hype for a long time and recently getting into the late model Six revolvers really made me think about the situation in a different way. Then thinking about it from a reloading perspective it really makes a lot of sense.

It's probably about time I pick up a vintage K, almost got a 66-1 snubby not too long ago it was even pinned and recessed. Only reason I passed is because it had a huge gouge, almost a chunk of metal missing in the frame under the firing pin. The company had a few 66's but it was the only one pinned and recessed yet it was cheaper than all the others. It was $525 or $550 and the others were pushing $700+. I figured there had to have been a reason for that so I trusted my instincts. Plus I'd much rather have a 3 inch 13 or 65 anyway. I've really been on a 3 inch kick recently.

I wonder, could someone with examples of all the variants post some pictures showing the various gas ring engineering changes so that I (we) could visualize exactly what is being talked about?

And I agree, I have a late 80s vintage 66 that I bought new in 1989, which has mostly been shot as a .38 Special. I do have a few thousand magnums through it, but I've never shot anything other than 158s, and usually my cast bullet reloads at a more sensible 1250-1300 fps. The gun has held up just fine

Patrick L said:

I wonder, could someone with examples of all the variants post some pictures showing the various gas ring engineering changes so that I (we) could visualize exactly what is being talked about?

And I agree, I have a late 80s vintage 66 that I bought new in 1989, which has mostly been shot as a .38 Special. I do have a few thousand magnums through it, but I've never shot anything other than 158s, and usually my cast bullet reloads at a more sensible 1250-1300 fps. The gun has held up just fine

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I could show you the changes that were made on the Rugers but I've never had a vintage K frame. Only reason I really knew about the Ruger changesis because I restored my late model Speed Six and when it came time to replace the cylinder it wouldn't work because I had got a cylinder that didn't have the gas ring attached. Figuring out that it was different from my early Security Six explained why the relief cut was necessary on the late model.

Gas ring on cylinder



Early model cylinder with no gas ring


Here's the yoke (crane) with the gas ring cut into it, having the gas ring on the front of the cylinder meant that no cut was needed on the yoke so this is an early model yoke. The late model doesn't have the cut. If S&W did the same thing it shouldn't have required taking more metal off. Hopefully someone can show us the differences in the K frame gas rings. The "gas ring" is the cut on the top right in front of the detent.

What is the purpose of the gas-ring ?

First off, I hope this worked. It's my first time posting pictures on the new format of the site. It seemed easier, but then again, we'll see...

Anyhow, I thought maybe instead of asking others to post pictures, I'd post pictures of MY gun, and the experts can tell me what I'm looking at. Here are shots of my 66-2, purchased new in 1989. There's a shot of the cylinder face, the yoke, and my forcing cone . So what part is the gas ring? Is it that flange on the end of the yoke barrel? Or is it the raised ring at the front of the cylinder surrounding the extractor rod? Also, my forcing cone has the tiniest flat spot on the bottom, but nowhere near as flat as I've seen on some in pictures.

Hey I think I did it!

jpage said:

What is the purpose of the gas-ring ?

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In a nutshell it helps direct the gases and keeps the inside of the cylinder from getting gunked up dirty. The cylinders that had it on the yoke would get sluggish in short order.

Patrick L said:

First off, I hope this worked. It's my first time posting pictures on the new format of the site. It seemed easier, but then again, we'll see...

Anyhow, I thought maybe instead of asking others to post pictures, I'd post pictures of MY gun, and the experts can tell me what I'm looking at. Here are shots of my 66-2, purchased new in 1989. There's a shot of the cylinder face, the yoke, and my forcing cone . So what part is the gas ring? Is it that flange on the end of the yoke barrel? Or is it the raised ring at the front of the cylinder surrounding the extractor rod? Also, my forcing cone has the tiniest flat spot on the bottom, but nowhere near as flat as I've seen on some in pictures.

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The gas ring is the metal ring on the front of the cylinder around the yoke. If you look at my above post it shows a Ruger cylinder with the gas ring and one without it. Yours has the gas ring.

I think when it comes to the relief cut on the forcing cone it just depends on who did the filing and how much clearance was needed for the cylinder to shut. I'm not 100% on that but if I had to guess that'd be my theory.

I was gifted a new Smith 66-1 when I obtained my degree from collitch and I was ignorant of their supposedly being issues with the forcing cone. I proceeded to spend, well going on 5 decades of running .357 through the revolver probably 30+% of the time and always preferred the 125gr bullet weight if that could matter and lighter bullet weight loads in .38spcl standard pressure and +P.
I just got through double checking the old girl and its forcing cone is just fine.
Methinks all this concern over the revolvers "weakness" is much ado about nothing.
OH, and some years later I bought on the cheap a Ruger Security Six that I have run countless rounds through and it too is issue free but then it always had that "tank" like feel to it. Both are superb guns with the Smith holding the "pretty" title between the two......and trigger title too.

barbarosa guns said:

I was gifted a new Smith 66-1 when I obtained my degree from collitch and I was ignorant of their supposedly being issues with the forcing cone. I proceeded to spend, well going on 5 decades of running .357 through the revolver probably 30+% of the time and always preferred the 125gr bullet weight if that could matter and lighter bullet weight loads in .38spcl standard pressure and +P.
I just got through double checking the old girl and its forcing cone is just fine.
Methinks all this concern over the revolvers "weakness" is much ado about nothing.
OH, and some years later I bought on the cheap a Ruger Security Six that I have run countless rounds through and it too is issue free but then it always had that "tank" like feel to it. Both are superb guns with the Smith holding the "pretty" title between the two......and trigger title too.

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Exactly! Much ado about nothing. Forcing cones have cracked but I don't think it's a widespread issue.

Your Security Six very likely has a full forcing cone with no relief cut. The gas ring change and relief cut was only during the last 3-4 years of production. It started in 1984 and the Security Six was discontinued in 1985 when the GP100 came out. The Speed Six and Service Six were produced until 1988, once the fixed sight GP100s and the SP101 came out the Six line was discontinued entirely. Unless yours dates to 84 or 85 then it very likely has a full forcing cone. Absolutely nothing to worry about in that case. Even if it did have the flat spot I wouldn't worry about. Every Six revolver I own is a late model with the flat spot and none show any signs of wear or erosion, I actually carry one with the flat spot.

The issue with Model 19 forcing cones cracking is not usually with factory loads, even 125 grain, as is is with handloaders hot-rodding 125 grain loads. It was not uncommon for some people to load the .357 Magnum to pressures hat exceeded SAAMI maximums for the cartridge attempting to get absolute maximum velocity with jacketed 125 grain bullets. Naturally people blamed the bullet weight and not the excessive pressures generated by their loads when they had crack occur. That is what appeared in all the gun rags!

It does happen and I have seen a few guns with cracked forcing cones, usually in the used gun case at a LGS. A close friend has one he bought used that is cracked too!

Back in 1981 I bought a new Model 19-5 S&W. I got the nickel version that was around $319 including tax. The blued version was around $20 cheaper but I liked the nickel one. Anyways there was the issue of what ammo to use. Ammo was very expensive so the first gun show I went to I bought a Lee 1000 and some Sierra 125 grain JHP's and some W296 powder. I maxed out the load using data from the Speer #8 manual that I bought the same day.

There was no internet then so there was not a herd of folks saying how badly I would damage my forcing cone and the top strap would be cut instantly.

Know what happened? I shot many pounds of powder and many boxes of 125 grain jacketed hollow points. I still have that revolver today. It is still a tack driver. None of that stuff happened. The internet is full of experts.

Alk8944 said:

The issue with Model 19 forcing cones cracking is not usually with factory loads, even 125 grain, as is is with handloaders hot-rodding 125 grain loads. It was not uncommon for some people to load the .357 Magnum to pressures hat exceeded SAAMI maximums for the cartridge attempting to get absolute maximum velocity with jacketed 125 grain bullets. Naturally people blamed the bullet weight and not the excessive pressures generated by their loads when they had crack occur. That is what appeared in all the gun rags!

It does happen and I have seen a few guns with cracked forcing cones, usually in the used gun case at a LGS. A close friend has one he bought used that is cracked too!

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I have to think that handloading was definitely a part of it, especially back in the 70s and 80s. I saw a Ruger GP100 a while back that had severe erosion on the forcing cone because the owner was loading 125s well above max with 296 and he was shooting hundreds of these hot reloads through it on a monthly basis. If I remember correctly it only lasted about 6 months before it gave out.

Model19man said:

Back in 1981 I bought a new Model 19-5 S&W. I got the nickel version that was around $319 including tax. The blued version was around $20 cheaper but I liked the nickel one. Anyways there was the issue of what ammo to use. Ammo was very expensive so the first gun show I went to I bought a Lee 1000 and some Sierra 125 grain JHP's and some W296 powder. I maxed out the load using data from the Speer #8 manual that I bought the same day.

There was no internet then so there was not a herd of folks saying how badly I would damage my forcing cone and the top strap would be cut instantly.

Know what happened? I shot many pounds of powder and many boxes of 125 grain jacketed hollow points. I still have that revolver today. It is still a tack driver. None of that stuff happened. The internet is full of experts.

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To be honest I've only seen a few sets of data from Speer #8, all I know is most people won't even quote the loads from that manual. I've been thinking about getting a reprint of it just to see for myself. I think the 38 special loads are the ones that got really crazy, I never hear too much about the 357 loads from #8. The main offender people mention is "The Load" of SR4756 for 38 special.

magnum0710 said:

To be honest I've only seen a few sets of data from Speer #8, all I know is most people won't even quote the loads from that manual. I've been thinking about getting a reprint of it just to see for myself. I think the 38 special loads are the ones that got really crazy, I never hear too much about the 357 loads from #8. The main offender people mention is "The Load" of SR4756 for 38 special.

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I don't know about that. I just used the 357 Magnum load that called out the Speer 125 grain jacketed hollow point and the powder was W296. Made a huge fireball and loud report. I think the max was around 22 grains so that is what I used.

I used the 38 Special data using 148 grain wadcutters and Bullseye powder. It was mild but pretty dirty. I can't say I ever tried their Dupont 4756 load.

19-2 no flat spot. I don't have a tool small enough to get in and measure O.D.

I contend in more than 3-1/2 decades of shooting and handloading and working with over a dozen different handgun-specific calibers, my favorite chambering of all must be the .357 Magnum. And when it comes to revolvers, there's nothing I love more than a pre-lock, pre-MIM, pre-frame mount firing pin S&W revolver.

For me, these are personal facts. Another fact? I do not enjoy the full-spec .357 Magnum cartridge in any K-frame revolver. I simply don't, that's just me. I don't personally believe it is as simple as being "recoil averse" because I will spend half a range day sending .460 Magnum at 200-400 yard steel plates, flinging 240gr XTP-Mag bullets out the muzzle of my 460XVR at 2,000 fps and never cry about the recoil.

I love the .357 Magnum cartridge from my N-frames. Don't like it from my K-frames.

And while this "K-frame magnum fragility" discussion happens a lot, I don't tire of hearing/reading the discussion and listening to the opinions and experiences of others.

With all that said... at long last, my point:

It does not seem to get mentioned that history suggests S&W did not intend the K-frame to be a platform for this cartridge. History suggests that S&W was pushed (pushed HARD!) in to the development of the Combat Magnum. And as mentioned, the .357 Magnum ammo available in 1956 or 1957 was different than the ammo that soon followed in the age of the light bullet, high velocity path that "working and social" ammo would take through the next many decades.

Someone posted above that they have a 19 dash something from 1981 and they've fed it a personal lifetime of 125's and their gun is perfect. All good. Can't say you're wrong.

I would challenge you to detail the countless thousands of balls-to-the-wall light bullet fodder it has digested if/when you sell it. Go ahead and add all your data in fantastic detail to the description of the revolver you're selling, I'm certain it will open up a wild bidding war with the number of interested parties rivaling the countless volume of full-test light bullet ammo you've sent through it.

Right -- I get it. You'll never sell it. That's cool, I'm simply trying to make a point.

Alk8944 said:

It does happen and I have seen a few guns with cracked forcing cones, usually in the used gun case at a LGS. A close friend has one he bought used that is cracked too!

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I bought a 66-1 6" from a private seller. Unaware of forcing cone issue. Gun shot fine for a few months, then locked up after a round. When I finally got it open I found the forcing cone cracked and displaced binding on the cylinder.

I don't like hot loads, so I never fed it any. When did the crack start, don't know.
The upside, I sent it to S&W they didn't have a 6" but they had a 4" to install, and replaced most of the firing group, $160..shipped.