Monel Rifle Barrel
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This is a bit of dangerous thinking. Not every peice of steel has the qualities of rifle barrel material.
Unless you have an analysis of the elasticity, tensile strength, exact composition, stress and heat treatment, and a dozen other factors, then you would be wise to proceed very carefully.
Steel is made in various grades for specific purposes. It has certain ingredients added to the raw ore when it is being made and it is laboratory tested to ensure these specifictions are held to a certain tolerance.
Many formulas of steel have been made into rifle barrels from low carbon soft SAE 1020 for .22 rimfires and muzzle loaders, up to 4140 Chrome Moly and some of the 300 series of Stainless steels, but even within these groups, not all are suitable candidates for a rifle barrel.
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This, in spades!
Being nickel based, it'll machine a little better than warm chewing gum.
But not much better.
Sell it for it's value and buy a decent barrel.
Buy a nice bar of 316 if you want a stainless barrel.
Cheers
Trev
The reson no one has really used it is that Monel is not suitable for a rifle barrel or action. The famous "Nickle Steel" Winchester and Springfield barrels and actions were a very high percentage of steel with only a small fraction of nickle added.
Monel Metal is generally 67% nickle, 28% copper and 5% other metals such as steel, manganese and aluminum. It is also more difficult to machine than stainless steel.
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http://www.specialmetals.com/documents/Monel alloy 400.pdf
http://www.atlassteels.com.au/documents/Atlas4140.pdf
For your viewing pleasure.
Sorry the 4140 one is in metric.
As you can see, when people talk about 'strength of 4140' they can be meaning some very different things, depending on heat treatment.
http://www.atlassteels.com.au/documents/Atlas4140.pdf
For your viewing pleasure.
Sorry the 4140 one is in metric.
As you can see, when people talk about 'strength of 4140' they can be meaning some very different things, depending on heat treatment.
Monel would be a fine material to make a barrel from. The reason they don't is cost.
Monel is 7-15 times more expensive than 4140 alloy and machining cost is 3 times as much, plus the tooling cost and wear is significantly higher. In the end it won't shoot any better than 4140 alloy or 400 series stainless.
So the only advantages to a monel barrel would be extreme corrosion resistance (storing it in battery acid) and much longer barrel life due to the work-hardening through use. It would be unlikely the extra life would justify the extra cost.
Someone had mentioned using 316 stainless. You would have to be careful using this as a barrel. The mechanical strength is not as high as 4140 alloy or heat-treatable stainless (400 series) that most manufacturers make barrels from.
From my experience gun barrels are tempered down to the softer side, too much hardness could effectively make it shatter. So having the correct heat treatment would also be important as using the correct material.
Monel is 7-15 times more expensive than 4140 alloy and machining cost is 3 times as much, plus the tooling cost and wear is significantly higher. In the end it won't shoot any better than 4140 alloy or 400 series stainless.
So the only advantages to a monel barrel would be extreme corrosion resistance (storing it in battery acid) and much longer barrel life due to the work-hardening through use. It would be unlikely the extra life would justify the extra cost.
Someone had mentioned using 316 stainless. You would have to be careful using this as a barrel. The mechanical strength is not as high as 4140 alloy or heat-treatable stainless (400 series) that most manufacturers make barrels from.
From my experience gun barrels are tempered down to the softer side, too much hardness could effectively make it shatter. So having the correct heat treatment would also be important as using the correct material.
Lee Enfield
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Stainless / monel is interesting stuff. Heating it and quenching it usually makes it softer....
It is my impression that monel work hardens fairly easily much like some stainless steels. While that statement seems to be at odds with it once being used for propellor shafts, I would worry about a monel barrel becoming brittle with use. If the barrel was a heavy one, that would probably not be a concern but possibly would be with a lightweight barrel
Even though some barrels are made from stainless, there are quite a few different stainless alloys and I am not convinced that all are suitable for barrel making
cheers mooncoon
Even though some barrels are made from stainless, there are quite a few different stainless alloys and I am not convinced that all are suitable for barrel making
cheers mooncoon
Oy vey! Yes, the hazards of not checking facts before posting. Again. 
Where I said 316 above, I was actually thinking of 416. I have a few pieces of 416, and can attest to it's machinability.
Hand a chunk of Monel to a barrel maker, and if he dos not tell you to #### right off, he has never tried machining the stuff. It really is slow paced misery to machine, and most of the machining processes used in barrel making (deep hole drilling, reaming,cut rifling) are pretty much the polar opposite of what works well for the high nickel alloys like this. Typically, those are processes that rely on a light cut, small chips, and decent machinability of the parent material.
I'd suspect that button rifling might actually work OK, just that getting the hole in there in the first place would be hellish. Typical machining on high nickel alloys involves a very slow moving tool, taking a heavy cut to get under the work hardened layer that was created on the surface left by the last pass.
Not saying it couldn't be done, just that it would be a costly exercise, for no real benefit.
Cheers
Trev
Where I said 316 above, I was actually thinking of 416. I have a few pieces of 416, and can attest to it's machinability.
Hand a chunk of Monel to a barrel maker, and if he dos not tell you to #### right off, he has never tried machining the stuff. It really is slow paced misery to machine, and most of the machining processes used in barrel making (deep hole drilling, reaming,cut rifling) are pretty much the polar opposite of what works well for the high nickel alloys like this. Typically, those are processes that rely on a light cut, small chips, and decent machinability of the parent material.
I'd suspect that button rifling might actually work OK, just that getting the hole in there in the first place would be hellish. Typical machining on high nickel alloys involves a very slow moving tool, taking a heavy cut to get under the work hardened layer that was created on the surface left by the last pass.
Not saying it couldn't be done, just that it would be a costly exercise, for no real benefit.
Cheers
Trev
OK - Did some digging... Monel has a yield of ~ 40 KSI... 4140 in its as received state, has a yield of between 60 and 90 KSI - ie without specific property enhancement by heat treatment.
Years ago, I did the hoop stress calculation on a Lee Enfield barrel, and came up with 44 KSI.... That piece of Monel is worth a fair amount of coin - likely to someone in the marine industry.
Years ago, I did the hoop stress calculation on a Lee Enfield barrel, and came up with 44 KSI.... That piece of Monel is worth a fair amount of coin - likely to someone in the marine industry.
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FWIW I have started making rifle barrels and barrel steel is identified as barrel steel [rifle barrel quality].
The barrel steel I use is 416 R , 416 modified and 4140 , the company that sells me the steel issues me the paperwork for it which shows the composition of the steel along with the mechanical properties.
Also it states the non distructive test used to insure the steel is perfectly homogenous no laps or inclusions .
Rifle barrel steel needs to be a steel that can handle suddenly applied pressures and not all steels are up to the task.
Some steels such as stressproof for an example show mechanical properties similar to barrel steels but is not suitable and would possibly blow up.
Rifle barrel steel when purchased has a tensile strength of about 125 000 lbs per square inch and is between 28-32 on the rockwelC scale for hardness.
Imo any steel that is not purchased as a rifle barrel quality steel is not suitable for making a barrel period.
The barrel steel I use is 416 R , 416 modified and 4140 , the company that sells me the steel issues me the paperwork for it which shows the composition of the steel along with the mechanical properties.
Also it states the non distructive test used to insure the steel is perfectly homogenous no laps or inclusions .
Rifle barrel steel needs to be a steel that can handle suddenly applied pressures and not all steels are up to the task.
Some steels such as stressproof for an example show mechanical properties similar to barrel steels but is not suitable and would possibly blow up.
Rifle barrel steel when purchased has a tensile strength of about 125 000 lbs per square inch and is between 28-32 on the rockwelC scale for hardness.
Imo any steel that is not purchased as a rifle barrel quality steel is not suitable for making a barrel period.
Coyote has it right. Monel is NOT steel. It is not suitable for applications requiring steel regardless of it's machinability. You might as well kick around the idea of making a rifle barrel from phosfor bronze or naval brass.
That's very interesting. Every barrel I have ever hardness tested is usually much softer. (closer to 20Rc).
I agree that every material is not suitable for rifle barrels.
I think the overwhelming theme is there is NO practical benefit to using monel for a barrel.
