S&W Model 66 and cracking forcing cones

[kym]

Is it the same for the Taurus 65?

"Smith and Wesson recommends that only 158gr loads in 357 magnum be used in the Model 66 and other K frame revolvers. The forcing cone is not as thick at the very bottom and can crack if using the 125gr loads. This is why S&W no longer makes a K frame 357 magnum. "

 

[GP100man]

If it has the flat machined to clear the cyl then YEP !!!

& if ya wanna keep it consider shooting mid loadings , keeping the hi pressure stuff to a very low minimum.

 

[kym]

The "flat" meaning the entrance of the cone?

 

[slick6]

He means the bottom of the forcing cone at the 6 o'clock position. Extermally, there is a flat there where the bottom of the forcing cone has been machined off-and, this is the area that can crack.

 

[kym]

I see. Thanks for the info.

 

[Loosenock]

Kym you should do a Google search on "Smith and Wesson forcing cone crack", I did. The model 66 is the stainless version of the Model 19. The forcing cone crack was in the model 19 and not the Model 66. What makes stainless steel stainless is chromium, 12% or better. And that when alloyed with steel makes the steel much tougher. Some of what I read, take it for what it is just a remark on the internet. That stainless guns are more difficult to machine the carbon steel guns. Reports claim many 1000's of rounds through each model without problems, but unheard of cone problems with the 66.

 

[16in50calNavalRifle]

kym - where was that block quote from? I assume it was a quote - though it was not formatted as such.

Loosenock - I have not looked into the topic extensively, but what I've seen does in fact only mention Model 19s and the cracked forcing cone problem. Other than the general point that stainless/chromium steel may be stronger than carbon, have you come across any specific info/research that clears the Model 66 of the cracking issue?

All - I have some 142g .357 ammo - wondering if that loading would qualify as a heavier one of the sort recommended to avoid the cracking problem? An interesting article pointed out to me by Radagast of the DOB thread above focuses on bullet length as the cause of gas cutting problems. In that case the bullets are 125g vs. 158g - any ideas on where a 142g loading fits in to this issue?

 

[BCRider]

The reading I've done in connection with the cracked cones on the 19's was in connection with the 110gn and to some extent 124gn bullets. At 142 gn you shouldn't have any issues even on a 19.

A couple of long time shooters I know used to have 19's that they used for shooting literally thousands of full power magnums from. They just plain wore out the guns timing wise and from flame cutting and stretching in one case but didn't crack the cones. But they stuck with using heavier bullets because they gave more recoil. And yes he admitted that they WERE young and foolish and were reloading for maximum flame and recoil so they put in some very stout loads that were likely up close to the SAMMI max.

 

[Loosenock]

16in50:

There is more reading about this than you can read in a month. Some of it is very interesting and has logical reasoning. It would be futile for anyone to compile a definitive resolution.

Searching "Smith Wesson model 66 forcing cone crack" on Google will bring results.

What I have found, and tend to believe is this.

There is more hype about the problem than the problem itself.

The problem exists in the model 19, I never read one documented or "Eye witness" account of it being in the model 66.

Several threads or locations mention that the model 66 no - was a different alloy. Maybe it had more chromium or maganese that made it tougher, I don't know. I also dont hold this statement the gospel truth unless I was to read it directly from S&W. But it is plausible.

The change from Model 66 to Model 66-1 was to move the gas ring from the yoke to the cylinder. This really wasn't so much an improvement. With the gas ring on the yoke made it difficult to clean the gas ring. If a large number of bullets were fired, lead buildup on the ring would cause the cylinder hard to rotate and stop. I actually experienced this personally after firing 500+ wadcutters in a S&W M10 (?? what dash, could have been an old M&P). But the lead was splattered on the face of the cylinder, gap between frame top strap and barrel, yoke and gas ring. It was a real mess and took several evenings with a bronze brush cleaning it up. So S&W moved the gas ring to the cylinder to make it easier to clean. Makes sense to me.

Back to the forcing cone. Cracks dont seem to occur if you use 158 gr. bullets and heavier. Why? I gathered this from reading. The 158 grain bullet is longer. As the front of the bullet leaves the cylinder it engages the forcing cone. The rear of the bullet is still in the cylinder and "seals", "somewhat seals", "more bullet the longer the seal and time to seal" the gases. When the rear of the bullet passes the cylinder there could be a somewhat pressure drop. A 125 grain bullet allows the gases in the chamber of the cylinder to escape quicker. The gases are a higher pressure and hotter which tend to cut the frame top strap and the thin portion of the forcing cone that is flattened. Thus weakened and now prone to crack. A person might want to concider what a continued diet of hot handloads, uncleaned revovers, and 5000 +P loads 125 grain bullets will do?

Please dont take my word for this. Just do a search of your own and draw your own conclusions. Share them with us. We all can learn more.

My own 2 1/2" 66 (no-) is incredibly accurate and I feel is the epitome of what a fine revolver should be. I know it will be passed down for generations to come.

Great topic.

'Loose

 

[16in50calNavalRifle]

BCRider - thanks for the info. For the usual reasons (mostly $$$$) I intend to mostly shoot .38 in the revolver, but of course will use some .357 also, so it's good to know the story.

 

[dfariswheel]

According to S&W, the "K" frames that cracked the cone were police issue guns shooting lighter very high velocity bullets AND had badly fouled forcing cones.
The fouled cones obviously played a part in the cracking.

The lighter bullets at very high velocity using very hot burning powders apparently subject the forcing cone to a form of metal fatigue. As the metal is fatigued it cracks, then breaks.

Most any small revolver with a smaller, thinner rear portion of the barrel may be subject to cracking as can larger guns with thicker barrel shanks. You just don't hear much about it.
In his shop manuals, Jerry Kuhnhausen showed pictures of Colt Pythons with cracked forcing cones.

To prevent any cracking of any revolver, limit the use of lighter, hotter loads and practice with the heavier bullet loads. Reserve most of the lighter bullet loads for actual "business" carry.
Second, buy a Lewis Lead Remover kit from Brownell's and use the forcing cone cleaner to keep the cone clean, whether you shoot lead or jacketed billets.

 

[GP100man]

The happenin with 125s is that the base of the bullet is even or past the mouth of the cyl & entering (being lined up in the forcing cone) as peak burn is reached , thus subjecting parts that would`nt be with a 158 or heavier bullet to hi speed particals & gases.

I`ll have to say I`ve only laid eye & hand on 1 model 19 with a cracked FC & I almost cried it was a recessed & pinned model !!

My flame throwing days are over & I enjoy loading & shooting midrange loads in `bout all my revolvers these days !!!

 

[John Wayne]

Here's my take on it:

Most of the cracked forcing cone reports came from the days when .357 factory ammo was loaded a lot hotter than it is today. Some of it was probably unsafe by today's standards.

125 gr. and lighter magnum loads seemed to cause a disproportionate number of cracked forcing cones.

I owned a model 65 (same as a 66, but with fixed sights) and fired thousands of rounds of ammo though it...mostly mild magnum loads (158 LSWC @1150 fps) and a few full powered ones. Never had a problem. Every Smith I've ever owned for any length of time has developed endshake problems though. I'd be more concerned with that than I would with a cracked forcing cone.

Regarding a Taurus, I don't know. They are generally of lesser quality regarding fit and finish, but that doesn't make them less durable. Personally, I wouldn't care about cracking a forcing cone in a Taurus because it's got a lifetime warranty.

 

[orionengnr]

Dfaris--
Great post.
I shoot my (one-time San Diego County Sheriffs) 66 no-dash fairly regulary, and carry it occasionally.
Think I'll buy a Lewis Lead remover and shoot and carry that M66 more frequently.

 

[kym]

I found it at http://guns.wikia.com/wiki/S&W_Model_66 I have owned mostly autos and just started picking up revolvers a couple of years ago. I have a CAI imported Taurus (65 it's blued) and have heard good and bad about Taurus. I mainly shoot .38 special and +P in it. I carry 160 gn hardcast when out in the woods but don't really shoot them a lot. The guy I got the +P from said he bought it by mistake for his .357 and was told he shouldn't use it. I didn't see a problem with using it but after reading the above, I thought I would ask.

 

[harmonic]

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.

 

[dfariswheel]

And you can reduce the risk while still shooting lighter bullets by buying the newer "short barrel" Magnum loads as made by Federal and others.
These have bullets in the 135 to 140 grain range and are getting a very good reputation,