Let's talk 1970s K frame magnums

[Mike LaNier]

Interesting stuff. I'm on board with Sevens post... I own two Model 19s and a Model 66, all shot quite a bit, and no indications of splits in the forcing cone, but I have seen that issue on others' guns. I do suspect, like others above, that excessive pressures are the culprit. While I hand loaded for years, I never exceeded recommended load data since I have seen cylinders split in two from injudicious overloads, and K-frames simply are not fun to shoot with heavy loa! In terms of the last point, it's pretty clear Sevens is right; S&W didn't intend for the K frame to be a Magnum frame...it came out in 1899, and Supica noted the K-frame .357 was built at the urging of Bill Jordan and came out in 1955; as a LEO gun, carried a lot and shot little? Could be! ML.

 

[bigggbbruce]

S&W didn't intend for the K frame to be a Magnum frame...it came out in 1899, and Supica noted the K-frame .357 was built at the urging of Bill Jordan and came out in 1955; as a LEO gun, carried a lot and shot little? Could be! ML.

I've never put a magnum round through this Combat Magnum
(I know, the gun is dirty. This was when I first got it home.)

 

[oneeyedpete]

the K-frame .357 was built at the urging of Bill Jordan and came out in 1955; as a LEO gun, carried a lot and shot little?

Exactly right!

 

[.357magger]

For m

 

[.357magger]

For me, the K frame is a 38 Special gun that can occasionally digest magnums. And it's not a mechanical issue for me, I simply find power levels above 38+P in a K Frame to be unpleasant to shoot more than a cylinder or two. (and don't get me started on J frames and 357s)

Slower follow up shots, excessive recoil impulse in a light frame...why go there and have an unpleasant training session. Particularly since I have a Colt Python (in regular EDC rotation) and Model 28 that eat Magnums like a bowl of M&Ms.

Just saying. YMMV

 

[Rock185]

My model 66 was manufactured in '72. I carried it for several years at work, shot it recreationally, etc., mostly with Magnum factory ammo and equivalent handloads. It didn't crack the forcing cone, but it was pretty loose when I sent it to S&W for an overhaul in '80. I did see a model 19 with a cracked forcing cone, and a Python with a bulged forcing cone. We were issued Winchester and Remington 125 grain . 357 JHPs at the time. Just one person's experience with Magnum ammo in a K-Frame..

 

[S&W Fan]

This 66-1 is from 1979. When I found it (gun only) the prior owner was running the Pachmayr Presentation grip-that had to go lol. Through the great members here I quickly first found a great set of factory presentation targets and then a set of Grashorn elk stags and a Tyler T. It seems to have led a very easy life, signs of perhaps spending more time in a holster or drawer than being fired. The action is fantastic, very smooth with the proverbial bank vault lockup and excellent timing.

I shoot .38spl ammo 99% of the time with a few cylinders of 158gr .357 at the end of the session. Got it out today for some drills after shooting the semi autos. The paper plates represent rounds at 7, 10 and 15 yards all double action with timed exposures of 3 seconds. All from the low ready position.

 

[AC Man]

My first revolver was a 1975 Smith 13 - 2 K frame 50 years ago. Have shot nothing but magnums thru it and it still looks likes new. Wasn't aware of the forcing cone issue till I got on the internet.

 

[Mr500cm]

I bought my first 66 back in the late 1980’s, 4 inches super accurate and a pleasure to shoot. This gun got me into reloading 148gr wadcutters and 158gr JHP, the only magnums I used were for hunting. The subject of forcing cones splitting never came up, it was unheard of. Now my original 66 is long gone but I picked up another one that maybe had 100 rounds through it. It looks and shoots great, now I’m no longer reloading and the only thing going through it is some Winchester 130gr FMJ at 800 fps so I’m not worried. I’ve been told that the stainless 66 K frames are more durable than the metal 19’s due to differences in the make up of the metallurgy, not sure how true that is. Most forcing cones that are split seem to come from the model 19 not 66.

 

[Tabby Lynn]

Exactly right!

My Dad was a police officer and his carry gun was a 4 inch S&W Model 19. We lived out in the country and could literally go shooting or hunting out the back door. He had built a 50 foot range in the backyard where he would practice on a regular basis. He taught me to shoot a handgun at 14, in the back yard with 158 gr semi wad cutters with the Model 19. When I went into the Army learned to shoot the 1911 and the S&W Model 10, 38 special 4 inch. I have a soft spot for the Model 19 and have had a few over the years. My other favorite handgun is my Colt Gold Cup National Match, followed by a Sig M17.

 

[magnum0710]

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

Wow, never knew that was possible with a vintage K. I wonder how many of those are out in the wild?

 

[magnum0710]

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.

That is true, they weren't intended for huge diets of 357 in the first place. For me the K frame and similar size guns in 357 are great for carrying full power 357. Small enough to conceal yet big enough to handle full power 357 with good control. Even with my K sized Rugers I shoot way more 38 than I do 357 but they still see a good amount of 357.

 

[magnum0710]

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.

It definitely has happened, I just don't think it's really a widespread issue. God knows how many rounds that 66 had digested before you got it. It could've started prior to you buying it, my 642 had a small chip on the outside of the forcing cone that I didn't notice at first, fouling covered it up. I didnt see until I got it home and cleaned it, it was a cosmetic issue more than anything but still.

 

[steelslaver]

The barrel shank is about .525 as K frame threads are .540 OD and about .007 deep. As the beginning of the forcing cone is just over .357 groove diameter and .525-.360=.165 your looking at just over .08 wall thickness once you divide by 2. Plus the early models need a small flat on the bottom so the gas ring and yoke cleared there.

A N frame 357 on the other hand has a .670 major OD before thread removal and about .655 after so .655-.360=.295 so it has around .147 walls

What is interesting is my 696 no dash L frame. With .562 threads which leaves around .55 shank after threads are gone. So .55-.434=.116 for .058 walls. Not much meat and the reason they went with a different forward lock up and .638 barrel threads on the model 69s in 44 mag.

 

[eclayton]

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.

Speaking of vintage loading tables, I don’t have Speer #8, but I started out in 1989 with a Ruger GP100 and a max load of Blue Dot behind a 158gr JSP from Speer #11. That load produced a tremendous fireball and blast. Before I learned any better, I discovered some pretty severe erosion on the GP100’s forcing cone and the beginnings of flame cutting on the top strap. That was after maybe 1,000 of those rounds. Meanwhile I shot 12 rounds of the same load through a Model 65, quit because it hurt my hand, and found when I got home that the timing was wrecked on two out of six cylinders.

 

[magnum0710]

Speaking of vintage loading tables, I don’t have Speer #8, but I started out in 1989 with a Ruger GP100 and a max load of Blue Dot behind a 158gr JSP from Speer #11. That load produced a tremendous fireball and blast. Before I learned any better, I discovered some pretty severe erosion on the GP100’s forcing cone and the beginnings of flame cutting on the top strap. That was after maybe 1,000 of those rounds. Meanwhile I shot 12 rounds of the same load through a Model 65, quit because it hurt my hand, and found when I got home that the timing was wrecked on two out of six cylinders.

Wow! I'm a little surprised by that one, I've never used Blue Dot but the guys that do seem to love it. Burn rate wise it's around HS6 and Longshot right? I know it's faster than 2400.

I tried to work up a 357 load using Win 231, I knew I wouldn't get magnum velocities but I thought I could get it above 38+p levels. No go, I wasn't even close to the max load and would get a pretty good flash. The recoil was extremely snappy too. I gave up on that one almost immediately. I'm betting the max load of Blue Dot now is lower than it was back then. I have some 38+p data from Hodgdon #26 that makes most current data look weak.

 

[tomhenry]

I don't remember where I got this, but it's an interesting read.

The 125 grain bullets driven to maximum velocities used large charges of relatively slow-burning powders. Handloaders know the powder types as WW296 and H-110, among others. The combination of slow ball-type powders and the short bearing surface of the 125 bullets allows prolonged gas cutting of the forcing cone and top strap area, accelerating erosion and wear.

Borescope studies of rifle, machine gun, and auto cannon chamber throats shows a lizzard-skin-like texture due to this gas cutting damage, called "brinelling". The results of brinelling are fine microcracks that weaken the surface of the steel, and further promote erosion. In machine guns and auto cannons, barrel life is measured in terms of "useable accuracy", and round counts that determine this are based on group sizes at engagement ranges.

In the K-frame magnums, the forcing cone dimensions combined with the barrel shank dimensions results in a relatively thin shank at the 6 o'clock position, where a machine cut is made to clear the crane. This is usually where the forcing cone cracks. The L and N frames use much beefier barrel shanks and do not have this cut. S&W intended the K frame magnums to be "carried much and fired seldom" service arms, designed to fire .38 Specials indefinitely, with light to moderate use of .357 Magnums. You notice that S&W has discontinued production of K frame .357 magnums, no doubt due to product liability issues and a couple generations of K frame magnum experience.

 

[eclayton]

Wow! I'm a little surprised by that one, I've never used Blue Dot but the guys that do seem to love it. Burn rate wise it's around HS6 and Longshot right? I know it's faster than 2400.

I tried to work up a 357 load using Win 231, I knew I wouldn't get magnum velocities but I thought I could get it above 38+p levels. No go, I wasn't even close to the max load and would get a pretty good flash. The recoil was extremely snappy too. I gave up on that one almost immediately. I'm betting the max load of Blue Dot now is lower than it was back then. I have some 38+p data from Hodgdon #26 that makes most current data look weak.

I was new to handguns back then and looking for the hottest load I could find. Now almost 40 years later I prefer .38s, not to spare the gun but to spare myself the beating. The tables for that load in Speer #11 advertised 1349 fps with a 158gr JSP. It was fun to shoot in the GP100, but not good for any gun. Primers were all flat with deep firing pin dents that sort of splattered around the edges like earth struck by a meteor—happily I never pierced one. It also annoyed other shooters because that load would rattle the whole indoor range and jiggle gear off people’s tables in the lanes next to me. To your original post, I think a cracked forcing cone may or may not happen in a K frame that shoots a lot of hot .357s, but damage to the hand and/or ratchet causing timing errors will surely happen and probably more quickly. Endshake probably also. Maybe the new production K frames can take it; the older ones are not made for that kind of beating.

 

[Harassor]

I have a 19-4 I bought used, perfect condition. The previous owner was LE but this was not his duty gun.

I gave my brother a 19-?, pinned barrel, years ago. I was young and punished it pretty bad. S&W made it like brand new and sent it home to me in a new box. Great gun, great company.

I have too many larger more powerful pistols to try and push this one too hard. It shoots gentle reloads, 158 lead, and otherwise sits at my desk where I'm typing this.

 

[magnum0710]

I was new to handguns back then and looking for the hottest load I could find. Now almost 40 years later I prefer .38s, not to spare the gun but to spare myself the beating. The tables for that load in Speer #11 advertised 1349 fps with a 158gr JSP. It was fun to shoot in the GP100, but not good for any gun. Primers were all flat with deep firing pin dents that sort of splattered around the edges like earth struck by a meteor—happily I never pierced one. It also annoyed other shooters because that load would rattle the whole indoor range and jiggle gear off people’s tables in the lanes next to me. To your original post, I think a cracked forcing cone may or may not happen in a K frame that shoots a lot of hot .357s, but damage to the hand and/or ratchet causing timing errors will surely happen and probably more quickly. Endshake probably also. Maybe the new production K frames can take it; the older ones are not made for that kind of beating.

I still get odd looks when I shoot factory 357 from a snubby at the range I scared the you know what out of some younger guys shooting 9mm the last time I went to the indoor range.

I believe the new K frames are made for 357, full forcing cone at least. I've never had a K frame but I have numerous Ruger Six revolvers and I love shooting 357 in them.