I put together and posted the below several years ago, and I am simply re-posting it here today. I still believe what I wrote several years ago. I have Mitch Yates building me a rifle right now and I have him using a GM barrel manly because of the type of steel the barrel is made from.
Some folks are simply not open to any information on this topic that is not the same as their opinion, and if you are one of those, please don’t read any farther, it is not my intent to get you all worked up. If you have an open mind and are willing to looking at some information I offer the following.
Let me first state that I am not a metallurgist nor am I an engineer. I do however have 30 years of professional experience in reviewing and evaluation of manufacturer’s of cargo tanks and other metal containers constructed of various metals for use in hazardous materials service. I am also trained in ASME boiler and pressure vessel code section VIII for construction of these vessels.
I also do not consider myself as an expert in this area. I have a working knowledge of metals and steel, but nothing close to being an expert. I do work with metallurgist on occasion and over the years have posed this question to them and also to a metallurgist that worked for a major steel mill. Each of them, without hesitation in short said no way would they ever use 12L14 for a ML barrel.
Some of the information that follows comes from the ‘Metals Handbook” I am not sure why they call it a handbook. It is one of those really big books and is 1,300 pages. I think it must weight 10 lbs. This book is a standard in the metal world and is recognized as one of the best “go to” books on metals of all types.
Measures of machinablility has been defined as a “complex property of a materials that controls the facility with which it can be cut to the size, shape and surface finish required commercially.” 1112 steel is rated at 100%. All other steels are rated above or below this 100% level, the majority falling considerably below. 12L14 is rated at 190%. Its machinability is a direct result of a fine dispersion of lead particles throughout the alloy.
12L14 is considered to be one of the fastest machining bar products produced today.
It is used to maximum advantage for parts where considerable machining is required such as bushings, inserts, couplings and hydraulic hose fittings. With good ductility, these grades are suitable for parts involving bending, crimping or riveting
12L14 is not used for gun barrels due to its strength and toughness, it is used because it is extremely easy to machine and cut the rifling in.
1137 was used by Green Mountain for ML barrels. 1137 is a known gun barrel steel and is considered a low cost, easy machinability and is rated at 160%. Some of the property numbers for 1137 are fairly similar to 12L14, but the overall characteristics are a bit different. My Metals Handbook even addresses the use of this steel for gun barrels.
4140 is/was used by Green Mountain for their bp cartridge barrels
This is one of the chromium, molybdenum, manganese low alloy steels noted for toughness, good torsional strength and good fatigue strength
As with all the low alloy steels forming may be done by conventional methods with the alloy in the annealed condition. These alloys have good ductility, but are tougher than plain carbon steel and thus usually require more force, or pressure, for forming.
Characterized by high strength and good impact properties with good machinability, but low weldability.
The following are properties for some of the common barrel steel used.
12L14
Tensile strength 78,300 PSI, Yield strength 60,200 PSI
1137
Tensile strength 108,000 PSI, Yield strength 76,100 PSI
1144
Tensile strength 108,000 PSI, Yield strength 89,900 PSI
4140
Tensile strength 148,000 PSI, Yield strength 95,000 PSI
The above numbers show what the tensile and yield strength for the 4 types of steels listed. The tensile strength gives us some idea on how tough the steel is. However, the standard for determining toughness is the Charpy V-notch test.
Notch toughness is the ability or capacity of a metal to yield plastically under high localized stress, such as might occur at the root of a notch. Notches may be inherent in design or may be the accidental result of tool marks, scratches, voids, minute surface cracks left by grinding, pits etc.
Notch toughness is influenced by the chemical composition and physical properties of the steel. Temperature can have a big impact (no pun intended) on failure of the Charpy V-notch test. As temperature decrease, the amount of energy the piece of steel is able to absorb decreases. This is called transition temperature. Once a piece of steel is at or beyond its transition temperature the toughness decreases rapidly and the ability for it to yield plastically and not fail is greatly decreased.
I am not 100% sure, but it is my understanding that 12L14 has a transition temperature around 70 degrees F. I have never worked professionally with 12L14 steel and have never witnessed or reviewed data for Charpy V-notch testing of it. If anyone has data that supports a different opinion of 12L14 for Charpy V-notch testing I would be interested in that.
I have 3 barrels made by Mark DeHaas and they are 1144. 1144 is not a great or even a good gun barrel steel as the physical properties are concerned. It is better than 12L14, but not by a large degree. These barrels are great for accuracy, simply wonderful and I love them. I can not say enough good things about Mark and his barrels. Several years ago he switched to using 12L14, when I asked him why, he stated for numerous reasons, cost, availability, easy of machining and because that is what many others are using.
If 12L14 was the only choice I had, or the best steel available it would make the decision much easier. However that is not the case in today’s world. As a consumer I can buy barrels from a few makers that are using steels that are recognized by metallurgist and engineers as an appropriate material for a gun barrel.
Do barrels made of 12L14 fail every day? Of coarse not. Have some failed? Of course. Might the failure be as the direct result of something the owner/shooter did that was not intended? Certainly. You ever shoot your ramrod? Not get a ball or bullet on the powder and leave a space? Double load your rifle?
Barrels made from steel that is recognized as good enough for a gun barrel can fail as well, however due to the physical qualities of the steel they have a better safety margin. Just like the ASME tanks that have a safety factor of 4 built into them. They are well built but unfortunately there are still failures.
I have several old shotguns that are ML and bp cartridge with damascus barrels, and I shoot them. The barrels on these guns are certainly not up to the standards for some of the more modern steels that we have available today. I realize that there is a certain risk associated with shooting these old girls. Back in the day that these barrels were made there were different quality as well as it comes to barrels. It is generally known that barrels that are not English barrels may cause one to have some concerns for quality. Belgium barrels are certainly not noted as being the standard of excellence. That does not mean that all barrels made in Belgium are bad barrels, and all English barrels are good. It is my understanding that my Parker 10 ga. hammer gun has Belgium barrels. Apparently that is where the Parker Company contracted to have their barrels made, and they are considered to be of high quality. This is why I try to only buy and use 100 – 150 year old guns from makers with known quality parts, including their barrels. In Greener’s book “The Gun” there is a fairly good section on barrels and construction of them.
Let me be clear, I have never stated that a 12L14 barrel will fail or is likely to fail. What I have stated and will state that 12L14 is not the best readily available steel to be used as barrel material, and if given a choice, I would not knowing own one. There are exceptions of course. If I had a 12L14 barrel in .32 cal. that was a 1” barrel I would certainly consider that over the same barrel in .54 cal. with a thinner wall thickness.
If you have the choice, why would you pick a barrel that is made from steel that is not recognized by any metallurgist as steel that is appropriate for a barrel? When it came time to buy the barrels for the guns I make I have been buying barrels from makers that use steel that is recognized by the steel industry has being barrel quality. Not because they are more accurate, simply because they are made from steel that is better suited for this purpose. Why would I knowingly use questionable parts for guns I am going to be giving my kids?
If you made it this far and you are still sure I am biggest idiot in the world and violently disagree with what I have stated above if you want to send me personal emails in that regard, go ahead. Most of them are quite humorous.
Like I tell my kids, life is full of decisions’, choose wisely.
fleener