K frame question

[BunkTheory]

Once read an article from the 1990s about a group of guys who were hot rodding GP 100s, using heavily pointed bullets and loads aproaching 60,000 cup or PSI on their testing gear. They said the guns were fine as the pointed bullet reduced stress when it entered the forcing cone.

Also read hints and suggestions here and there that the use of wadcutters was a bad idea as the flat front increased impact stress on the forcing cone slightly. Never had any indication of by how much the stress was increased.

So we all know the super light weight bullets and magnum loads, and shooting lead and jacketed bullets without proper cleaning in between the two types of bullet helped create the forcing cone crack issue.

Im just curious as to how much the cracking was impacted by officers using their duty guns for Bulls Eye shooting and PPC shooting with wadcutter loads... some guys claimed 10,000 rounds minimum a year for shooting and practice for contests so im just thinking on the correlation.

[rintinglen]

Very few officers used their duty revolvers for that level of use. If you were into PPC, at least by the late 70's, you shot a gun specifically tuned and prepped for PPC. The duty gun stayed in the locker when not in service, save for the occasional "duty gun" match or qualification.

I sold my Davis PPC gun in 1984 with 34,000 rounds through it--by me, how many the guy I bought it from had previously sent down range is a question I can't answer. 2.7 grains of bullseye under a Remington or Speer HBWC, or 3.0 grains under a cast 148 button nose wad cutter simply don't generate that much pressure, and consequently, not that hard of an impact. It was still serviceable, and smooth, albeit worn.

[Boolit_Head]

Back in the 80's I was one of those running my duty gun in early ppc competition. Some weeks my 686 was fed around 800 rounds a week. They were everything from wad cutters to jhp depending on what I had or cast then it would get cleaned up and loaded with silvertips for duty use. I stayed with published loads at the time and never had any issues. That gun still sits in my safe as a prized possession with no issues. If you go back to my load books I used then the loads of today seem lighter but I suspect a lot of the issue was running to hot and to heavy. The K frame is good but within it's limits. Quality wise I also would not compare a older Smith K frame to a Ruger GP100.

[Outpost75]

K frame will not stand up to high volume use of plus-P or .357 loads. Customs and Border Patrol tests of 1980s made this very clear. If you want to PM me with an email address which I can receive 20MB of .pdf attachments I can send to you.

Stick to standard-pressure .38 Special if you want the gun to last.

[TNsailorman]

I have seen a cracked forcing cone and the guy was pushing the limits with 125 grain jacketed bullets, plus P+. He admitted himself that it was a stupid thing to be shooting +P loads and the 125's for everyday use. I will not now or ever push a steady diet of +P loads through my Model 13. I carry +P for defense but that is all, they will never be a day to day load for me at the range. It is other peoples revolvers and they can do as they please, but not me. james

[Outpost75]

Read Mike Wood's article on Revolver Guy about barrel cracking on K-frame S&W.
Very through and well researched.

[tazman]

I had a model 19 forcing cone crack on me. Until the edges bent far enough to bind the cylinder, it didn't pose a problem or any accuracy issues.
I relegated it to 38 special wadcutter use until somebody made me a stupid high offer for it due to it's accuracy.
That would have been back in the early eighties and as far as I know, the man still uses it for wadcutter shooting. He knew the cone was cracked when he bought it but didn't care.

[RJM52]

I know one guy who cracked the forcing cone on a 60s vintage Model 15 with 110 grain Sierra JHC bullets and I believe SR-4756 powder that got the load into the 1200s...

My only long term experience with a K was a 1970 vintage 4" Model 19-3. Had a documented 10k rounds through it 90+% of which were the 158 grain Lyman/Thompson gas check bullet that was going 1200 fps. It went back to the factory for a tune up and was nickled. Another 10K went through the gun before it was sold in 1980. In that 20K rounds only 6 rounds of .38 Special ever went through the gun. I only had four revolvers and one 1911 at that point so it got shot a lot.

Shot one PPC match with that gun in 1977, won my class, found it boring, found IPSC and shot it till 1995...

Bob

[FergusonTO35]

K frame will not stand up to high volume use of plus-P or .357 loads. Customs and Border Patrol tests of 1980s made this very clear. If you want to PM me with an email address which I can receive 20MB of .pdf attachments I can send to you.

Stick to standard-pressure .38 Special if you want the gun to last.

Agree 100%. If you can't get the job done with a decent standard pressure load, you probably need to move up to a bona fide .357 revolver. My 10-5 loves 3.4 grains Bullseye under the Lee 358-158-RF. Accurate, easy to shoot, and smacks targets with authority. If I need something more than that I'm grabbing a rifle!

[Boolit_Head]

A lot of the +P loads were in the 357 range. I had some heavy 296 loads from that era for my 357 that just hurt to shoot.

[carelesslove]

carelesslove, here !

"OLD" gun sages (and I am 68) have always seems to "have it in" for the Model 19 - as it seems to have been the "original" target of the cracked forcing cone phenomena.

There might be a good reason for this. If we were look very closely at an older vintage Model 19, and move the cylinder to the open position, we could all observe the small, almost imperceptible flat spot at the bottom of the barrel, where the cylinder / gas ring "almost" comes into contact with the barrel.

This might hold the answer and pinpoint the weakest link in the K Frame design - when fired with loads at higher pressures.

This small flat spot visibly reduces the distance that escaping powder has to travel, before it dissipates its energy. If we see and understand how forcing cones erode - an inside-to-outside radial pattern - it might be easier to understand why the Model 19 barrel cracks at the 6:00 position.


S&W engineers of the early 1950's probably expended a lot of effort in changing the barrel / cylinder / frame material to a chrome / moly alloy to make it heat "treatable", and therefore - much stronger. More than likely, if our Model 19s didn't erode their forcing cones, we might never think there was a problem shooting "modern" .357 Magnum ammo in them. Even with the "flat spot", the Model 19 forcing cone area is plenty strong, but it is probably not strong enough, when the radial wear cuts across the flat spot.

When this occurs, the stress on the barrel cross-section goes "sky high" and it invariably cracks.

Let's make a clear delineation here. You really don't see a lot of N Frame barrel / forcing cone cracks - do you? If you look at the back of the barrel on an N Frame, it has no flat spot. Approximately 50 years ago, I only had one gun - a 4" Model 28-2. I learned to shoot, cast bullets and reload with this gun. I was a greasemonkey at a gas station and had a seemingly limitless supply of (good) wheelweights. I tried to shoot this old 28 to death and almost succeeded. I managed to burn off the back of the barrel and completely erode anything that resembled a forcing cone. It looked like 80 grit sandpaper. Back then, S&W had a good laugh at me - and replaced the barrel for free!

But, there were no cracks..........

I know and understand the advent of the "hotter burning" ball powders and the quest for lighter bullets at higher velocities - I tried it myself. But, if you fire enough "magnum-level" rounds with virtually any powder / bullet combination, you will erode your revolver's forcing cone and the back of the barrel. The Model 19 just has its' own, unique limitation.

Standard velocity / pressure cartridges, like the .38 Special - operating at ~15,000 psi - just don't "burn up" their barrels. Raise that pressure to 35,000 psi - with the same geometry and the forcing cone game changes. Admittedly, the use of chrome-moly steel helps, but time & pressure will take its' toll.

I still own, shoot, and enjoy my 19-2 and a slightly newer 66-1. I try to take care of them and keep the velocity (1000 ft/sec) & pressure (~20,000 psi) down, while still shooting them a good bit. I have not seen any measurable erosion at ~1000 ft-sec, but every now and then I do step it up a little.

As I age (at an increasing rate) I am getting a little more recoil-sensitive and keeping velocities below sonic levels might prolong my failing sense of hearing, but when I experience "the need for speed", I go to the N Frames and save the K Frames for yet another day of lower pressure shooting.

The K Frame .357's are great revolvers - just try to resist pushing them past their limitations.

I hope my opinions & rambling sense to all of you.

Tom "carelesslove" Love

[TNsailorman]

careless, I enjoyed your piece and you pointed out something that I should have but left out because I have been told I did not know what I was talking about when I pointed to that flat spot on the bottom of the forcing cone. I am convinced that it is the weak spot in the K frames. But ammunition can play apart also. I bought a box of Remington 125 grain .357 a few years ago and it was really hot. There was a noticeable difference between the ammo in that box and other .357 I had tried out in in new Model 13 before. There was a very bright flash and more noticeable recoil from the ammo in that box. When I got finished shooting the box up and started to clean the revolver, I found the ammo in that box had cut a noticeable "flame cut" in the top strap. Remington must have used a very fast and hot burning powder in that loading. I never bought any more of that Remington offering. James

[brassrat]

I had some of that Rem. It was 125 gr SP and lots of kick. I bet there are 6 or 12 kicking around in multi load boxes I put together

[BunkTheory]

Read Mike Wood's article on Revolver Guy about barrel cracking on K-frame S&W.
Very through and well researched.

I dont want to hurt your feelings but i saw that website last night, and that website left me with some very unpleasant feelings. I havent seen that level of elitist attitude outside of video game/computer forums in quite some time.
I really appreciated reading that i was little more then an inbred child molesting, wife beating toothless hillbilly with webbed toes suckign on my thumb if i had a gun that wasnt made by kimber, colt, smith wesson, ruger, korth, or didnt have a specific make and model of holster, or didnt use a specific brand or grain weight of ammunition in my fire arm.

[M-Tecs]

Read Mike Wood's article on Revolver Guy about barrel cracking on K-frame S&W.
Very through and well researched.

This one is excellent also https://revolverguy.com/the-smith-wesson-l-frame-story/

[M-Tecs]

I dont want to hurt your feelings but i saw that website last night, and that website left me with some very unpleasant feelings. I havent seen that level of elitist attitude outside of video game/computer forums in quite some time.
I really appreciated reading that i was little more then an inbred child molesting, wife beating toothless hillbilly with webbed toes suckign on my thumb if i had a gun that wasnt made by kimber, colt, smith wesson, ruger, korth, or didnt have a specific make and model of holster, or didnt use a specific brand or grain weight of ammunition in my fire arm.

Which article are you referring too?

[BunkTheory]

Its just that with the 38 +p+ Treasury Load still being available, And a new super vel out on the market pushing a 90 grain hollow point to about 1300 fps in a 4 or 6 inch barrel, I really got to thinking as 110 and 125 are considered the minimum/"ideal" for self defense by the gun rags and gun websites.

[BunkTheory]

I read the whole website last night, the curse of insomnia. There are some rants about "that not so smart guy who just bought his first gun" that include alot of elistist insults to those who dont have a 300$ custom holster, or a kimber, sw, colt, ruger, korth revolver.

[tazman]

Its just that with the 38 +p+ Treasury Load still being available, And a new super vel out on the market pushing a 90 grain hollow point to about 1300 fps in a 4 or 6 inch barrel, I really got to thinking as 110 and 125 are considered the minimum/"ideal" for self defense by the gun rags and gun websites.

At one point, the 357 with a 125 grain hollow point was considered the best one shot man stopper available. This was before the development of our current hollow points in 9mm, 40S&W, 45ACP, etc.
I suspect some of those writers have never tested any of the new stuff with an open mind.
The fun part is, all the old cartridges that were successful all those years ago, are still quite capable of doing the same job now. They didn't suddenly lose the ability to cause bad guys to stop doing bad things. Other stuff just got better than it had been previously.
A deadly weapon is still deadly no matter how old the concept is.
As to the FBI load still being available, all those old revolvers didn't just vanish from the earth. They still work and still need fed a good load that does the job.

[Outpost75]

I dont want to hurt your feelings but i saw that website last night, and that website left me with some very unpleasant feelings. I havent seen that level of elitist attitude outside of video game/computer forums in quite some time.
I really appreciated reading that i was little more then an inbred child molesting, wife beating toothless hillbilly with webbed toes suckign on my thumb if i had a gun that wasnt made by kimber, colt, smith wesson, ruger, korth, or didnt have a specific make and model of holster, or didnt use a specific brand or grain weight of ammunition in my fire arm.

No hurt feelings here. I have no interest at all in reading about new products and models. I am a dinosaur for whom an old gun that works is worth more than a new one that doesn't. Mike has some good technical and historical articles and those are the ones I read.

I'm not into $300 holsters or $6000 revolvers either. I own five shooter - grade Colt New Service revolvers and a couple Gen1 Colt SAs and I didn't spend $1000 for any of them.