Discussion in 'Gunsmithing and Repairs' started by MUSICALGUNNUT45, Nov 18, 2011.
Someone smarter than me will be along shortly to tell us how it REALLY works
Machinery's Handbook published by Industrial Press Inc. It describes in detail the processes and controls required to produce all possible properties available to most gun metals.
Provided you know the properties of your gun's metal.
In any case, steel's interesting properties are it's yield strength and it's ultimate strength. Heat treating does not increase a steel's ultimate strength, it can only affect it's yield strength by bringing the yield up to anything very near the ultimate strength. In a pressure vessel you want to design a yield failure long before you have an ultimate failure i.e. a bulge or crack before a brittle fracture or shatter.
Either failure is bad but one is worse than the other.
Stress corrosion and hydrogen embrittlement is also a greater problem in high strength steels than it is in lower tempered steels resulting in fewer stress cycles before potential failure.
In the mid-1950's, Bill Jordan suggested to S&W that they build a medium frame revolver, which was easier to carry and handle by the average cop. S&W changed the heat treating of the K frame which allowed use of the .357 Magnum in the K frame. Later, when Winchester developed the 125gr JHP round, it was discovered that this hot round caused end shake, top strap flame cutting, and premature forcing cone erosion.
The K frame just wasn't designed to handle a steady diet of .357 Magnums. Thus, S&W developed and produced the L frame, which solved the problem.
There are also reports, not verified, that stainless steel K frames have some dimensional differences than carbon steel frames. But no one has ever confirmed this.
S&W also changed the heat treating of the N frame when the .357 Magnum round was originally developed in 1935.
As others have previously mentioned hardening steel is virtually a two-edged sword.
re-heat-treat a metal after it has already been done once, either. As Clifford stated, you can't harden a metal to the point where it becomes brittle. A piece of tempered glass (e.g., an auto side window) is hard, but if struck with a concentrated force it will crumble into thousands of pieces. A diamond is the hardest substance in the world, but if you try to cleave a piece off it and do it incorrectly, it will similarly shatter.
Heat treating does not increase a steel's ultimate strength,...
I think something got garbled there. For example for 4140:
95 ksi tensile, 60 ksi yield in the annealed contidion
257 ksi tensile, 238 ksi yield hardened and tempered to 510 HB
(source, ASM Metals Reference Book, 2nd ed)
For the OP: I'm a hobby metalworker. I have the heat treat oven, the Rockwell tester, and so on, and have heat treated knife blades, springs, and so on. I would not in my wildest dreams redo the factory heat treat on anything safety critical - guns, car suspensions, etc. It's just too easy to get it wrong (and too likely the factory already got the optimal balance). Moreover, it's hard to say what the weak link of a design actually is; if you make a 1911 barrel stronger and shoot uber hot loads you may just find that the link was the weak part. To look at it another way, what reason would a factory have to ship a gun with nonoptimal heat treatment? It doesn't cost more to do it right.
factory checked around 28 on the Rockwell Hardness Tester. The cylinders
checked 43. I heat treated the frames to 43 same as the cylinders. This was
just done on the frames only. Nothing else. They were made of 4140 chrome
moly steel. I have one Ruger in 45 Colt that I did this to that has been shot
4.000 times with very Hot Hot loads with no ill effect. I'm talking near 50.000
psi. This was over 40 years ago. This is all the experence I have on it.
Nope: In both cases they used they're standard KT or NT frame. What they did do is make the cylinders out of a different alloy steel, with a double-heat treating process. During the 1990's modifications were made to beef up both frames in certain critical places, but I don't believe any changes were made in material/heat treating specifications.
The weakest link in the chain is the brass case that creates the chamber seal when the gun is fired.
If the brass case lets go and releases chamber pressure into the action, the gun will let go, regardless of what steel it is made from, or how it is heat treated.
"Heat treating does not increase a steel's ultimate strength,..."
I'll just go sit over here until I figure out what in the world I was trying to say.
I have one Ruger in 45 Colt that I did this to that has been shot
4.000 times with very Hot Hot loads with no ill effect.
I don't know the round count but a friend shot a .45 NM Blackhawk with magnumized loads until the transfer bar was pounded too thin to "transfer". So he took it out and ground the hammer to hit the firing pin directly, then shot it until the forcing cone eroded thin and cracked. Ruger replaced the barrel and all the working parts for a modest fee; but the stock "soft" frame was just fine and he kept on shooting it for the rest of his life.
This is true only if whatever you're shooting doesn't have a fully supported chamber.
This is true only if whatever you're shooting doesn't have a fully supported chamber.
As for the heat treating question, you don't want "hard" steel, you want "tough" steel.
A hard, brittle receiver or barrel is the last thing you want. That's why many early receivers were case-hardened. The outside is hard for wear resistance, but the inside is still ductile.
Making any particular steel alloy harder makes it more brittle (the yield and ultimate strength points become closer together). That's well illustrated in post #10. Annealed 4140 has an ultimate strength 58% greater than the yield strength, with a Brinell Hardness (BH) of about 300. hardening it to a BH of 510 gives an ultimate strength only 8% above the yield point. In other words, there's not much room for error. Glass is hard and brittle, try bending or impacting a sheet of glass. The yield point is the same as the ultimate strength point. That's not what you want on a gun.
Lot's more goes into the metullurgy of a gun than just the hardness. Trying to second guess the factory heat treat of your gun is a good way to make a grenade.
If it has an extractor, or a primer, it is not fully supported.
Thats why bolt-action & single-shot rifles can be blown up with an over load.
The brass lets go at the extractor cut, or the primer leaks bad enough to melt the case head, and away we go!
So according to you there's no such thing as a centerfire pistol or rifle with a fully supported chamber?
Here's a quick example, you don't believe Barsto knows what they're talking about?
Storm Lake and KKM Precision appear to equally deluded, perhaps you can enlighten them:
A revolver cylinder, even a DA with extractor star, has more case support than an auto. A SA revolver has the most case support of any handgun, maybe of any gun. But it is still possible to expand the casehead, blow the primer pocket and cause a lot of excitement.
PO Ackley considered a rimmed cartridge in a properly chambered barrel with minimum extractor cut to be the strongest proposition.
While Roy Jinks is not more specific in his book, I will quote him as follows:
Mr. Jinks' writing leads the reader to conclude that the cylinder was not the only component to be treated differently. He specifically uses the term "guns", and not "cylinders".
I stand by my original post.
I've heard of it being done to some custom rifle barrels (to what benefit, if any, I'm not sure). But that is at the time of manufacture; I am pretty sure you don't want to take a new gun and immerse it in liquid nitrogen.
Those companies advertise barrels that offer full support to the limit that the design allows. As rc said...If it has a ramp, an extractor, and a primer...the case doesn't have 100% support...not even with zero headspace.
Maybe I can enlighten you to something. Snark and condescension don't work out well whenever somebody with experience provides a straight, factual answer to a serious question in the course of a civil discussion, and it won't likely generate any helpful responses when it's your turn to seek helpful responses. rc may not have all the answers, but he's got a throwdown bunch of'em and they come from experience...not what he read in an advertisement.
Nothin' but love...
No big deal if you're like rcmodel and also don't understand firearm chamber terminology. The chamber has NOTHING to do with whether a particular cartridge has a primer or not. The CHAMBER is the part of the barrel that accepts the cartridge. If it FULLY surrounds the cartridge, it is a FULLY SUPPORTED chamber. If it is relieved for a feed ramp (or whatever), it isn't FULLY supported.
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