Where is the strength located?

"...Heat treating is time consuming and adds expense..." And requires machined surfaces to be surface ground after.
Anyway, you really cannot compare how LEO firearms are used as most are carried a great deal more than they're fired. Including practice that usually doesn't happen.
The difference between a .38 and .357 is the metallurgy and thickness of the cylinder walls and the frames.
 
Jim,
Specialty guns may be heat treated, but most guns aren't.
In my gun engraving experience, the only gun that I encountered that was surely heat treated was a Colt Woodsman slide! Why? I don't know, but it was almost as hard as my gravers.
Of course, modern guns with surface heat treatments like the Glocks are out there.
 
It is commonly said on the S&W board that they started heat treating cylinders in the 1920s.
The .357 Magnum was advertised as having a "Heat-treated chrome nickel steel" cylinder.
Caspian says their slides are "struck on Caspian dies and pre-heat treated to 37-41 RC before they ever see a cutting tool to insure dimensional stability."
Jac Weller reported in American Rifleman that when the .444 Marlin was new on the market, Marlin was sending barrels to Remington to be zone heat treated on the breech for the higher pressure, larger diameter cartridge.

The gun business is not run like Forged in Fire, heat it up orange hot and quench til a file skates. Heat treated parts don't have to be left glass hard to where they have to be ground instead of machined.

If heat treatment was so difficult, why does S&W and Colt bother with the even more elaborate case hardening process? Not like they are making guns out of wrought iron and low carbon steel any more.

I don't know about that Woodsman slide. A friend once laboriously dovetailed a Woodsman slide for a Low Micro with hand tools, hacksaw and files.
My 1979 S.M. ACE has a rather soft slide, the slide stop notch is peened.
 
The only one I have numbers for is Caspian; 4340 at RC 37-41.
That calls for quench from 850C (1557F) tempered at maybe 530C (986F.)
Annealed 4340 is RC 17, full hardened looks like RC 50.
 
If a gun was designed for only low pressure rounds, in many cases it was completely re-engineered into a stronger frame, stronger,stiffer steel, thicker walls, so forth. There are many points of potential weakness.

We started, for example, with the .38 colt. We had to redesign the gun to use the special. Right now, there are many guns from the past that should not fire plus pressure. Later, the .38 special was boosted to the power and pressure levels of a .357 load, and this was named the .38-44, because it was not to be fired with a standard frame, only the frames built for .44 special. Over time, a beefier revolver was designed by several companies to withstand the new .357 magnum round.

There are many areas of weakness that need to be addressed when increasing power, and there are many measures taken to strengthen those guns.

It's quite surprising, at least to me, that my .357 and my .38 look and feel so similar. The additional strength was not chained by simply adding on a lot of steel everywhere, it was carefully done with many small improvements.

I believe that one of the most important steps was simply changing from plain steel stock to better, stronger alloys.

Do a bit of reading on Damascus shotgun barrels for a very good example of old vs New, and these dangers.
 
Some years ago I toured the Smith & Wesson factory in Springfield, Mass.

I was somewhat surprised to see all steel brought into the factory was in the form of round bars, maybe 3" in diameter and about twenty feet in length. Carbon steel and stainless steel could only be identified by the color painted on the end of the bars.

A section was cut from the bar and taken into the foundry where it was trip-hammered in the rough shape of a frame. From the forge it went into what looked like a Post Office delivery truck (without wheels) and was further machined by high speed cutters cooled by the flow of a turquoise colored liquid. Cylinders were cut from the stock and machined. Barrels were done much the same way. The parts were then inspected by a robot that picked up each piece from a conveyor belt and either accepted or rejected. Then parts went into a room with ovens, which tourists were prohibited from entering. But on the other side trays of very hot parts passed by the tour at a safe distance. Again tourists were barred from the bluing area, and parts came to a workman seated at a bench who assembled the revolvers. I especially noted that at his bench was a lead rod about twelve ~ fourteen inches long, about an inch in diameter, with a rubber bicycle grip on one end. If there was any binding of the action, the workman used this lead "hammer" to give the revolver a swift "WHACK!" and the gun was well timed and fitted.

Bob Wright
 
Why would a manufacturer not heat treat a gun to the metal's strongest potential without regard whether it is for a .38 Spl. or a .357 Magnum?
Click to expand...

Same reason they don't use stronger alloys where it isn't needed. Cost.
Click to expand...
Can you explain how drawing to, say 35 on the Rockwell C Scale and compared to 40 would affect cost?
 
I especially noted that at his bench was a lead rod about twelve ~ fourteen inches long, about an inch in diameter, with a rubber bicycle grip on one end.
Click to expand...

At one time, if you went to S&W Armorers' School, you would be given your very own Babbitt Bar. The toolbox size is only about half as long as the factory fitter bar you saw.
 
Howdy

First of all, let's understand something.

With a revolver, it is the cylinder that must withstand the pressure generated when a cartridge fires. Not the frame, not the backstrap, and not the barrel. The cylinder is the pressure vessel that contains the pressure. Yes, the frame must withstand the battering of recoil, but the frame is not subjected to the pressure generated by a cartridge firing. Neither is the barrel. I'm a little bit hazy on this, but pressure is already leaking out of the barrel/cylinder gap as the bullet passes into the barrel. And pressure may be dropping as the bullet proceeds down the barrel. In any event, even with an old 'pencil barreled' S&W, the barrel wall is at least as thick as the cross section between the chambers of the cylinder. Yes, I have measured.

Regarding cylinder diameter, just grabbed an old 38 Military and Police (38 Special), made in 1939, a Model 10-5 (38 Special) made in 1964, a Model 13 (357 Mag) made in 1979 and my old Model 19-3 (357 Mag) made in 1975.

Guess what? With the exception of the Model 19, all had cylinders 1.440 in diameter. The Model 19 cylinder was slightly larger in diameter, 1.453. That's .013 larger in diameter. Not much.

Forget the length of the cylinders. That has nothing to do with how strong the cylinder is. Yes, means a 357 Mag cylinder will be long enough to chamber the longer Magnum rounds, but it has nothing to do with the strength of the cylinder.

The thinnest, and therefor weakest portion of any cylinder is not usually the web between chambers. It is usually the area under the cylinder locking slot. Between the bottom of the slot and the underlying chamber. Most cylinders tend to have the leading edge of this slot perfectly lined up with a chamber, pretty much guaranteeing that is the thinnest bit of metal on the cylinder. And if a cylinder ruptures, that is usually where the rupture starts. High speed photography has verified this. Rugers are different. Old Bill Ruger realized this was the weakest point of a revolver cylinder, so he moved them slightly away from the center line of the chambers. If you have a cylinder with an odd number of chambers, such as my seven shot Model 686, the slots are between the chambers, but with an even number of chambers, the slots are nicely lined up with the chambers.

Here is a perfect example. I am not clear any more if this old Merwin Hulbert cylinder was blown up by Black Powder or by Smokeless, but that is besides the point. Notice how the rupture started right at the locking slot, then propagated forward and back. Notice how the slots on either side of the chamber that failed are starting to fold in. A bit more powder and they would have failed too. That is very typical of a burst cylinder, three chambers get daylighted.

blownmerwinhulbertcylinder02_zpsd6b45aad.jpg



blownmerwinhulbertcylinder01_zpse057ebd4.jpg





As the pieces of cylinder take off, they usually take the top strap with them.

blownupmerwin_zps8337ec48.jpg



I have seen lots of cylinders blown up this way. I seldom see a barrel blown up. If something is going to burst, it is usually the cylinder. If the barrel bursts too, it was a huge overload.

Not talking about rifles, shotguns or semi-auto pistols. Talking about revolvers.
 
I was somewhat surprised to see all steel brought into the factory was in the form of round bars, maybe 3" in diameter and about twenty feet in length. Carbon steel and stainless steel could only be identified by the color painted on the end of the bars.
Click to expand...

Hi Bob. I saw the same thing at S&W. Everything came in as round stock. Short lengths were cut from the stock to be sent to the hammer forges. Unfortunately, we were not allowed to see the forging operation. I too was surprised that frames started as round stock, but that's how it is done. When you think about it, that makes the most sense. Round blanks to not have to be oriented. Once they are struck and take their first shape, they are then moved to progressive cavities for further striking and shaping. At some point tooling holes are drilled or stamped onto the forgings so the parts can be accurately placed on the CNC fixtures.

Somewhere on the web is a video showing Smith and Wesson frames being forged. I cannot find it, but this video is very good. It shows parts being forged in progressive molds. After a few strikes, the part is moved to different cavities to progressively shape the parts.

https://www.youtube.com/watch?v=5vK9tVsizSk


This Smith and Wesson video is pretty useless because it does not show anything in motion. But about 20 seconds in you can see forged frames ready for CNC. The tooling holes are visible. The parts will be dropped over pins in a fixture to locate the parts for the CNC machine.

https://www.youtube.com/watch?v=3v8YxQeq6v4



The day I visited S&W, there were bins and bins full of X frame forgings ready for CNC.

When the new factory was built around 1950, they found that the foundation of the old factory had been cracked by years and years of the hammer forges pounding away. An interesting point is that there are only two hammer forges at S&W. Across town at the Springfield Armory there used to be a room full of them.
 
Thank you Bob Wright and Driftwood Johnson for the information.
I am thankful folk like you and others here on the forum are still willing to share your knowledge and experiences with the rest of us.

When I was a kid there was a documentary series on TV called 'Industry On Parade'. (There are copies of the show on YouTube.) The show was a blatant love fest for manufacturing and I liked it a lot. I think some of the cable networks have 'how it's made' type videos today but I don't think they have the background to do a good job and they probably wouldn't do firearms manufacturers anyway.

Sigh.

I do remember an article somewhere about S&W, I think it was before the British company took them over, where there was a finishing room with one long, long, long axel running the length of the room near the ceiling and each station had a belt running up to the power axel. The power axel was always turning, when you got ready to work you threw in a tensioner pulley and then your device was spun off the main power axel. Different stations had different sized pulleys depending on if they wanted more speed or less speed than the power axel provided. It really looked like something from the 1910's or 1920's but it wasn't that long ago they were still doing business this way.
 
That's the way most factories were powered before small electric motors became practical. I used to work in an old mill that still had the iron hangers on the walls that the drive shafts used to hang from.

These photos are from a mill down the street from where I live. The first two photos are of the old stationary steam engine that used to power the mill. There were originally two of them, next to each other. One has since been removed, and this one is painted up very nicely as a display, but it no longer functions.


Over_All_View.jpg


Over_All_View_02.jpg




Here is a view of some of the overhead pulleys still in place that were powered by belts from the steam engines. Many of the drive shafts are still in place, even though they are not powered anymore.

Pulleys_02.jpg





These photos are from the Colt factory in 1938. Long after modern electric motors were developed, but these machines were all belt driven from overhead shafts. Each machine had a clutch to pick up power from an overhead shaft. Notice there are no guards of any kind on the belts. Serious accidents were frequent.

shop%20machinery%20colt%201938_zps0xo7uyl4.jpg


machinery%20colt%201938_zpss3lt6vkt.jpg
 
Last edited:
The easiest and cheapest way is to pick steel that can be HT'd in the steel mill , then formed , then ready to go ! Many automobile parts are done this way. HT' steel then formed and welded with no further HT.
Ask a metallurgist , he will at least get you confused ! :p
 
If i have understood correctly, the steel used for "Magnum" frames, barrels and cylinders is actually a different alloy than that used for standard pressure calibers, not just a different heat treatment. The goal is a material that is not especially surface hard (as in case hardening) but is tough all the way through.

"...but the frame is not subjected to the pressure generated by a cartridge firing. Neither is the barrel." Not true; while the frame is not a pressure vessel, the frame is certainly subject to the back-thrust of the case and that is caused by the pressure generated by the burning of the powder. The barrel, of course is a pressure vessel; if not, why not make barrels of aluminum or plastic?

Jim
 
The easiest and cheapest way is to pick steel that can be HT'd in the steel mill , then formed , then ready to go !
Click to expand...
I am confused. I thought heat treatment (most of the time), consisted of a hardening process then drawing to give up some of the hardness to get strength. If the steel came from the mill already hardened and drawn, would not the machinability of that steel be problematic with conventional machine tools? I was under the impression that steels arrive from the mill in an annealed state. Is that not true?
 
Depends on the user's specs.
More rigid machines and harder cutters make it possible to work with pre-hardened steel. Caspian says they do. It avoids worries over warpage when heat treating finished parts. The Luger was "soft fit" and then "hard fit" after heat treatment.
 
James K

I stated that the frame must withstand the battering of recoil. That is another way of stating 'the frame is certainly subject to the back-thrust of the case and that is caused by the pressure generated by the burning of the powder.'

Regarding barrels and cylinders and pressure. I am certainly not suggesting making barrels out of aluminum or plastic. What I said is, "I'm a little bit hazy on this, but pressure is already leaking out of the barrel/cylinder gap as the bullet passes into the barrel. And pressure may be dropping as the bullet proceeds down the barrel."

I have not seen any statistics regarding how much pressure the barrel sees as the bullet travels down the barrel. I would love to see some.

With a perfect load, pressure would remain constant as the bullet traveled down the barrel, and as the bullet exited the muzzle the powder would have been completely consumed, so pressure could drop to zero. Of course such a perfect world does not exist and muzzle flash tells us that some of the powder is still burning as the bullet exits the barrel.

Regardless, it is the cylinder that must contain the initial pressure spike as the bullet accelerates out of the cartridge case. Whether the pressure continues to build as the bullet travels down the barrel I do not know. I do know that most of the time, when a revolver blows up it is the cylinder that bursts, not the barrel.

The OP's original question, 'where is the strength located', was a little bit vague. In my not so humble opinion, it is the cylinder that sees the brunt of the pressure spike. As I stated, barrels have thicker walls than the narrowest cross section of a typical cylinder. If anything is going to blow, it is the cylinder. Even if the shooter gets a bullet stuck half way down the barrel, when the next bullet strikes the stuck bullet, it will usually bulge the barrel, or blow the cylinder. The barrel is strong enough that it will usually not burst.
 
You must log in or register to reply here.
Back
Top