View Full Version : Superalloy barrels
Some time ago, I heard about nickel based superalloys with cobalt based linings being used to make machine gun barrels and tested for some military applications. Today I happened to stumble across this:
http://www.dtic.mil/ndia/2016armament/18355_Armstrong.pdf
I'm sure it would be overkill for a semi auto AR, but I wonder how likely it would be that these would end up on commercially available rifles down the road. While we're on the subject of superalloys, I also came across a patent from 2012 for John Noveske. It was for an extreme duty machine gun barrel made of H13 tool steel. Pretty tough stuff. This is the same alloy Wilson Combat manufactures their TTU triggers from.
http://www.google.com/patents/US8333029
Thoughts?
Tspeis
Planning on shooting 350 rpm - sustained?
If not, nitriding is adequate and chrome plating is over-kill....
There is an interview out there on the web with John Noveske. These barrels are touched on.
He basically said they were not finically viable. The alloy destroyed tooling. Each barrel had to be sold in the 1000-1500$ range. However they did not last long enough to justify over buying 2-3 of his normal stainless barrels so they never went into full production.
What about gas tubes? Those seem to rupture before the barrel during sustained full auto, right? I wonder how that would hold up paired with a Stellite lined barrel and what the cost would be.
What about gas tubes? Those seem to rupture before the barrel during sustained full auto, right? I wonder how that would hold up paired with a Stellite lined barrel and what the cost would be.
Vseven makes an Inconel one for ~60$
http://www.vsevenweaponsystems.com/collections/upper-parts/products/v7-extreme-environment-gas-tube
Planning on shooting 350 rpm - sustained?
If not, nitriding is adequate and chrome plating is over-kill....
Negative, but just because my intended application doesn't include sustained full auto fire doesn't mean an alloy more resistant to heat and throat erosion over what's currently available isn't desirable. Some of the larger magnum calibers burn through barrels pretty quick and they're not even gas guns. I understand the price of ammo it would require to burn through a barrel could easily pay for another barrel, but if something better came along at the same price point as current barrels, I'd see no downside to trying it.
There is an interview out there on the web with John Noveske. These barrels are touched on.
He basically said they were not finically viable. The alloy destroyed tooling. Each barrel had to be sold in the 1000-1500$ range. However they did not last long enough to justify over buying 2-3 of his normal stainless barrels so they never went into full production.
I don't think any H13 barrels were ever sold. Are you sure the interview was about the H13 tool steel barrels and not the 17-4 PH stainless ones? I recall this about the 17-4 PH extreme duty barrels he was doing a while back, but I don't remember seeing anything about the tool steel though. Not saying it isn't out there, I just haven't seen it.
Tspeis
17-4PH is an amazing material. I know John Noveske made a 17-4PH barrel for a M249, however I never heard if any other barrels were made from 17-4PH.
Nickel alloys with cobalt alloy liners? sounds like big $$$ to me. Probably could buy at least 2 CHF barrels and quite a few more regular barrels for the increased cost at a SWAG. If you get more than double the life of a CHF barrel then it might be worth it but that seems like a stretch....
ColtSeavers
06-17-16, 13:04
I'm still just waiting for someone to CL a nitrided 41V50 barrel... Seems quite simple enough.
The new Hodge Defense CHF barrels use a proprietary steel and are claiming to be stronger and more accurate than current military barrel offerings, designed to leverage the hard hitting, but high pressure M855A1 ammunition.
fallenromeo
06-17-16, 14:31
Vseven makes an Inconel one for ~60$
http://www.vsevenweaponsystems.com/collections/upper-parts/products/v7-extreme-environment-gas-tube
interesting. But I fail to understand, why? Anyone can correct me if I am wrong, because I am far from the expert most in here are, but my understanding is the gas tube is meant to be a sacrificial part. It is designed to blow before the barrel does, and is cheap enough to replace without destroying your entire barrel. Using a part like this that is designed to stand up longer to a rigorous firing schedule means it won't blow, and thus there is a greater chance of your barrel going before this does. Isn't that counter to what it was originally designed for?
I'm still just waiting for someone to CL a nitrided 41V50 barrel... Seems quite simple enough.
You can do that yourself.
Buy the chrome plated, 41V50 barrel of your choice, and send it out to be nitrided.....
There you go.
ColtSeavers
06-17-16, 14:40
You can do that yourself.
Buy the chrome plated, 41V50 barrel of your choice, and send it out to be nitrided.....
There you go.
I was actually thinking of it as someone Nitridring a 41V50 barrel first, and then Chrome Lining it.
Can Chrome be Nitrided? (with no detrimental effects, gain any benefits)
Coal Dragger
06-17-16, 15:07
I don't think so, you'd have to nitride the barrel and then chrome line it as you stated. My understanding is that Chrome will not benefit from feritic nitrocarbuerization.
That would make for one very tough barrel, however I wonder if the benefits would justify the extra cost?
ColtSeavers
06-17-16, 16:41
I don't think so, you'd have to nitride the barrel and then chrome line it as you stated. My understanding is that Chrome will not benefit from feritic nitrocarbuerization.
I remember reading that it's not viable as well when researching barrels in the past, but I do not remember where and therefore until I can find it again I will simply stay under the impression that it shouldn't be and ask anyone that says otherwise if they can explain why it can be.
That would make for one very tough barrel, however I wonder if the benefits would justify the extra cost?
Should be relatively cheap and easy to execute as well considering how commonplace both barrel finishes are and when compared to super and/or rare alloys/metals.
ColtSeavers
06-17-16, 17:28
Found this while researching where I had read about whether chrome itself can be/should be nitrided.
Q.*Is it possible to chrome plate over a nitrided part? —M.M.
A.*Yes, you can chrome plate over a nitrided part. The most critical part of the process is to etch the surface properly prior to plating. Acids should not be used in this process because of the risk of hydrogen embrittlement. Two possible ways of preparing the surface is using sandblasting or tumbling. After plating, the parts should be heat-treated.
http://www.pfonline.com/articles/hard-chrome-on-nitrided-parts
Feritic nitrocarburizing is, by definition, done on steel. Chrome is chrome, not iron so there is no ferrous material to nitrocarburize.
This discussion does make me wonder about the ability to plate chrome alloys onto a bore.
ColtSeavers
06-17-16, 21:29
http://www.bluehogreport.com/wp-content/uploads/facepalm.jpg
http://www.lightworkersworld.com/wp-content/uploads/2013/10/Cant-See-the-Forest-for-the-Trees.jpg
Found this while researching where I had read about whether chrome itself can be/should be nitrided.
http://www.pfonline.com/articles/hard-chrome-on-nitrided-parts
You can chrome plate over a nitrided surface, however, the benefits are not additive in this application. You do not get the added life of a nitrided bore plus the added life of the chrome plated bore, you only get the added life of the chrome plated bore.
Otherwise big really high pressure, hot burning, guns would use this technique to improve barrel life. The M256 120mm tank gun has a chamber pressure in the 85,000 psi range, propellant flame temperatures about 1000 degrees hotter than 5.56mm, and a full charge barrel life of 1500 rounds. If they could get as little as a 10% increase by chrome plating over a nitrided surface, they would do it.
ColtSeavers
06-18-16, 10:57
You can chrome plate over a nitrided surface, however, the benefits are not additive in this application. You do not get the added life of a nitrided bore plus the added life of the chrome plated bore, you only get the added life of the chrome plated bore.
Otherwise big really high pressure, hot burning, guns would use this technique to improve barrel life. The M256 120mm tank gun has a chamber pressure in the 85,000 psi range, propellant flame temperatures about 1000 degrees hotter than 5.56mm, and a full charge barrel life of 1500 rounds. If they could get as little as a 10% increase by chrome plating over a nitrided surface, they would do it.
As I posted in the quoted link, the benefit of nitriding a barrel is removed if the nitrided layer of the bore must be removed to allow chrome plating (not uncluding the benefit of the outside of the barrel being nitrided).
My curiosity comes from whether the nitrided layer within the bore must be removed to allow chrome plating to begin with, or if something can be changed in either procedure to allow the to barrel finishes to be applied and have thier effects remain inact to additively applied.
You say that a barrel can be nitrided and then chrome plated, assuming the nitrided layer within the bore remains intact and the chrome plating applied over it, why, exactly, are the effects not cumulative or additive?
Your second pargraph in the post I quoted does not help me understand. I am not trying to be obtuse, but I do admit to having not read up on the subject in some time and being not as interested in the topic as I once was.
And no, I do not subscribe to the line of thinking that just because it's not being done that way that it means that it's already been tried, tested and found wanting. I need a bit more than that.
As I posted in the quoted link, the benefit of nitriding a barrel is removed if the nitrided layer of the bore must be removed to allow chrome plating (not uncluding the benefit of the outside of the barrel being nitrided).
My curiosity comes from whether the nitrided layer within the bore must be removed to allow chrome plating to begin with, or if something can be changed in either procedure to allow the to barrel finishes to be applied and have thier effects remain inact to additively applied.
You say that a barrel can be nitrided and then chrome plated, assuming the nitrided layer within the bore remains intact and the chrome plating applied over it, why, exactly, are the effects not cumulative or additive?
Your second pargraph in the post I quoted does not help me understand. I am not trying to be obtuse, but I do admit to having not read up on the subject in some time and being not as interested in the topic as I once was.
And no, I do not subscribe to the line of thinking that just because it's not being done that way that it means that it's already been tried, tested and found wanting. I need a bit more than that.
Well, the M256 is a smooth bore tube, so it is of no particular problem to machine them oversized to accommodate the additional thickness of chromium. Since nitriding adds no additional thickness, there is no reason to remove the nitrided surface in order to plate it.
As to why they don't use it I cannot give an answer, other than to offer these two choices, 1) all the major caliber gun manufacturers, BAe North America (formerly United Defense), General Dynamics (Saco), Alliant, Mesa and Watervliet Arsenal as well as all the small caliber barrel manufactures like Colt and FN are complete idiots; all willing to spend millions of dollars since the late 1970 on things like explosive tantalum cladding or plasma spray as alternatives instead of a relatively inexpensive and simple plating over nitride, or 2) there is some technical reason why it is not worth the effort. You can pick your favorite.
There are many reports on how to increase barrel life published by the USG out there free for the reading, there are also as many more that are not released to the public.
BufordTJustice
06-19-16, 00:14
Obviously, a stellite liner for the chamber, throat, and first few inches of barrel would allow for higher rates of fire (and, ostensibly, longer life), but the liner would be virtually impossible to machine on any kind of production scale/pricing structure.
Does anybody know what alloy Hodge Defense is using?
Obviously, a stellite liner for the chamber, throat, and first few inches of barrel would allow for higher rates of fire (and, ostensibly, longer life), but the liner would be virtually impossible to machine on any kind of production scale/pricing structure.
Does anybody know what alloy Hodge Defense is using?
I believe the steel alloy Hodge Defense is using for their CHF barrels is 9310H .
Stellite liners bring a few problems of their own, such as lining up the rifling between the liner and the rest of the barrel.
However, stellite lined machine gun barrels have been used for years.
Well, the M256 is a smooth bore tube, so it is of no particular problem to machine them oversized to accommodate the additional thickness of chromium. Since nitriding adds no additional thickness, there is no reason to remove the nitrided surface in order to plate it.
As to why they don't use it I cannot give an answer, other than to offer these two choices, 1) all the major caliber gun manufacturers, BAe North America (formerly United Defense), General Dynamics (Saco), Alliant, Mesa and Watervliet Arsenal as well as all the small caliber barrel manufactures like Colt and FN are complete idiots; all willing to spend millions of dollars since the late 1970 on things like explosive tantalum cladding or plasma spray as alternatives instead of a relatively inexpensive and simple plating over nitride, or 2) there is some technical reason why it is not worth the effort. You can pick your favorite.
There are many reports on how to increase barrel life published by the USG out there free for the reading, there are also as many more that are not released to the public.
to know exactly why it's not done you'd have to know the exact requirements spec for the item in question. could be different in each one. I wouldn't even swag at an answer though
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to know exactly why it's not done you'd have to know the exact requirements spec for the item in question. could be different in each one. I wouldn't even swag at an answer though
Sent from my SAMSUNG-SM-G930A using Tapatalk
Note that it is not done for small arms barrels either. They still use just chrome plating, M4s, M16s, M249, M110, etc. Yet, this application is also subject to millions in research for ways to improve barrel life....
Note that it is not done for small arms barrels either. They still use just chrome plating, M4s, M16s, M249, M110, etc. Yet, this application is also subject to millions in research for ways to improve barrel life....
oh yeah I know. was just adding some to your point. There's some reason it isn't done but real hard to know what that reason is
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vicious_cb
06-19-16, 23:17
Stellite liners bring a few problems of their own, such as lining up the rifling between the liner and the rest of the barrel.
However, stellite lined machine gun barrels have been used for years.
Fine for a MG barrel but the decrease in accuracy wouldn't be worth it in a rifle or carbine nor the decrease in corrosion resistance.
In the history of the Ordnance Dept. the research personnel were always looking for ways to extend bore life and help stop corrosion. Plated and lined bores were the answer. A plated bore is one which is chrome plated, usually from the beginning of the chamber to the muzzle. This helps fight the battle against rust and gives the bore a considerably longer life. A lined bore is one which has a 9 inch stellite liner, which starts at the end of the chamber. Stellite is an incredibly hard material and was used only in machine gun barrels. Aircraft machine gun barrels with stellite were rated at 6-7000 rounds of life, versus 1500 for unlined barrels of the same type. Stellite, although it does not have the same resistance to rust as chrome, will extend barrel life far beyond that of chrome.
vicious_cb
06-26-16, 00:31
Here is some light reading on the subject of the .mil testing various barrel linings/platings for 5.56 SAW barrels.
http://www.dtic.mil/dtic/tr/fulltext/u2/822736.pdf
Here is some light reading on the subject of the .mil testing various barrel linings/platings for 5.56 SAW barrels.
http://www.dtic.mil/dtic/tr/fulltext/u2/822736.pdf
Actually, the testing in that report was done with the Stoner 63 belt fed machine gun, XM207
vicious_cb
06-26-16, 15:16
Actually, the testing in that report was done with the Stoner 63 belt fed machine gun, XM207
Considering that's the title of the paper, the stoner 63 was probably what was considered the 5.56 SAW back in 1967. It was a damn good system too.
Considering that's the title of the paper, the stoner 63 was probably what was considered the 5.56 SAW back in 1967. It was a damn good system too.
???
The title of the paper is "Development of a Stellite-Lined, Chromium-Plated Barrel for [a] 5.56 mm Machine Gun."
The this study fell under the Small Arms Weapons System (SAWS) Project, which is a completely different from the later Squad Automatic Weapon (SAW) Project. A final "S", for one thing, but the main difference was the SAWS Project was a general study to improve infantry weapons, not a search for a specific weapon. The SAWS Project also included studies with flechettes, duplex rounds, and rifles without sights for snap-shooting....
EDIT: Oh and the XM207 was classed as a Light Machine Gun, not as a Squad Automatic. The Stoner that was the Squad Automatic was the BREN-looking thing that was never given a military "XM" designation.
vicious_cb
06-26-16, 17:39
???
The title of the paper is "Development of a Stellite-Lined, Chromium-Plated Barrel for [a] 5.56 mm Machine Gun."
The this study fell under the Small Arms Weapons System (SAWS) Project, which is a completely different from the later Squad Automatic Weapon (SAW) Project. A final "S", for one thing, but the main difference was the SAWS Project was a general study to improve infantry weapons, not a search for a specific weapon. The SAWS Project also included studies with flechettes, duplex rounds, and rifles without sights for snap-shooting....
EDIT: Oh and the XM207 was classed as a Light Machine Gun, not as a Squad Automatic. The Stoner that was the Squad Automatic was the BREN-looking thing that was never given a military "XM" designation.
Thanks for the background info. I wonder if they ever did adopt stellite lined 5.56 barrels. My internet searching cannot find any info on the subject other than the recommendation of using stellite.
interesting. But I fail to understand, why? Anyone can correct me if I am wrong, because I am far from the expert most in here are, but my understanding is the gas tube is meant to be a sacrificial part. It is designed to blow before the barrel does, and is cheap enough to replace without destroying your entire barrel. Using a part like this that is designed to stand up longer to a rigorous firing schedule means it won't blow, and thus there is a greater chance of your barrel going before this does. Isn't that counter to what it was originally designed for?
It is meant as a "cool" part, and also meant on the serious side for "Hey, I may trash this barrel during the Battle of Wanat, but I can still launch fast things from the flashing end, and that might just keep me alive rather than dead with a still okay barrel".
Thanks for the background info. I wonder if they ever did adopt stellite lined 5.56 barrels. My internet searching cannot find any info on the subject other than the recommendation of using stellite.
Not for 5.56mm MGs, the cost of manufacturing stellite lined barrels exceeded the added barrel life. A good chrome-plated barrel is a single part with basically three close tolerance operations - Boring/rifling, chromium plating, chambering. A stellite lined barrel is an assembly of at least three parts - the chamber, the liner and the barrel, each with a number of close tolerance operations, the barrel and liner have to be made so they can be shrunk fit, and have the rifling line up, the chamber has to closely fit the barrel and liner, etc, etc.
It was done for the .50 cal and the M240, although, I don't know if it is still done, it may just be cheaper to have more chrome-plated barrels.
Stellite liners are used in the M2 .50 cal and the 7.62mm M60 machinegun.
The British tried Stellite liners in their MAG-58 general purpose machineguns but they dropped them for cost.
Nitriding is cheaper than chrome lining.
With either treatment, once you start into cyclic and sustained automatic fire when the barrel reaches 500 to 600 degrees Centigrade the steel is irreversibly changed. When at 500-600 degrees the barrel steel will actually be softer than the bullets' copper jackets and the bore surface will start to wear (crack and chip away). Copper-washed steel bullets will wear your bore faster than copper-jacketed lead bullets.
Stellite has a higher heat resistance rating than steel due to higher cobalt and chromium content.
Chrome-lining a nitride barrel is going to make that tube even more expensive -- especially if it will ever be abused at high-temperature full-auto -- then what's the point? There would be no savings.
A Stellite-lined M240 barrel will do 18,000 rounds while a chrome-lined will do 10,000.
For a semiautomatic rifle the Stellite liner will probably not offer the same level of precision as Stellite is normally cast and ground and not cut.
Hammer-forging and nitriding will probably be more economical than chrome-plating for semi-auto use. All barrels need to be stress-relieved (normally by heating or oil-quenching. Cryo treatment will help finish the austenite to martensite conversion in a barrel's steel alloy).
It doesn't take long for a 5.56mm M16 or M4 barrel to fail at close to cyclic rate without cooling: http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA317929
interesting. But I fail to understand, why? Anyone can correct me if I am wrong, because I am far from the expert most in here are, but my understanding is the gas tube is meant to be a sacrificial part. It is designed to blow before the barrel does, and is cheap enough to replace without destroying your entire barrel. Using a part like this that is designed to stand up longer to a rigorous firing schedule means it won't blow, and thus there is a greater chance of your barrel going before this does. Isn't that counter to what it was originally designed for?
It is meant as a "cool" part, and also meant on the serious side for "Hey, I may trash this barrel during the Battle of Wanat, but I can still launch fast things from the flashing end, and that might just keep me alive rather than dead with a still okay barrel".
Neither are supposed to fail under normal operation. Normal, being defined as 90 rpm for about 2 minutes.
The gas tube has a good to 7x safety factor at room temperature a at least 3x at 2000 F.
If you shoot an M4 fast enough to trash the gas tube the barrel is toasted, your hand guards are on fire, and you are stuck with a very awkward straight-pull rifle. An M16 will usually pop a barrel before the gas tube, the M4, it's reversed.
Neither are supposed to fail under normal operation. Normal, being defined as 90 rpm for about 2 minutes.
The gas tube has a good to 7x safety factor at room temperature a at least 3x at 2000 F.
If you shoot an M4 fast enough to trash the gas tube the barrel is toasted, your hand guards are on fire, and you are stuck with a very awkward straight-pull rifle. An M16 will usually pop a barrel before the gas tube, the M4, it's reversed.
Sounds good in theory, and is usually more accurate on. Middy and rifle length systems, but on sbrs, this is not necessarily the case. Gas tube dies first. You need to really romp on it with an nfa lower, but it can and does happen. Especially on the shorter sbrs. Point being, I'd rather stop when I want than when something breaks.
Stellite liners are used in the M2 .50 cal and the 7.62mm M60 machinegun.
The British tried Stellite liners in their MAG-58 general purpose machineguns but they dropped them for cost.
Nitriding is cheaper than chrome lining.
With either treatment, once you start into cyclic and sustained automatic fire when the barrel reaches 500 to 600 degrees Centigrade the steel is irreversibly changed. When at 500-600 degrees the barrel steel will actually be softer than the bullets' copper jackets and the bore surface will start to wear (crack and chip away). Copper-washed steel bullets will wear your bore faster than copper-jacketed lead bullets.
Stellite has a higher heat resistance rating than steel due to higher cobalt and chromium content.
Chrome-lining a nitride barrel is going to make that tube even more expensive -- especially if it will ever be abused at high-temperature full-auto -- then what's the point? There would be no savings.
A Stellite-lined M240 barrel will do 18,000 rounds while a chrome-lined will do 10,000.
For a semiautomatic rifle the Stellite liner will probably not offer the same level of precision as Stellite is normally cast and ground and not cut.
Hammer-forging and nitriding will probably be more economical than chrome-plating for semi-auto use. All barrels need to be stress-relieved (normally by heating or oil-quenching. Cryo treatment will help finish the austenite to martensite conversion in a barrel's steel alloy).
It doesn't take long for a 5.56mm M16 or M4 barrel to fail at close to cyclic rate without cooling: http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA317929
Just a few things:
Not all M2 HB or M60 barrels are Stellite lined.
Newer production M2 HBs (p/n 7266131) are lined, some of the older ones aren't.
The .50 cal M85 MG did not use a Stellite liner.
All older M60 barrels (p/n 7269027) are not lined, for recently produced barrels, only the M60E3/Mk43 used a Stellite liner.
There is at least one company in the U.S. that makes Stellite lined barrel for the M240/MAG-58, I don't know who exactly buys them.
And, the M1919 barrel, p/n 7162295, was Stellite lined.
As to the M16/M4 barrel failing, note that in that report all weapons tested had a barrel failure first.
I know this is a bit of a necropost, but...
I have owned a rifle since 2015 that took WAY lighter a buffer than it should have, to run. A V7 Inconel gas tube was installed from the word "go". No binding. No patency issues. No fitment problems.
Finally, I removed said tube, and installed a microbest (Daniel Defense). The gun immediately began cycling the way it was intended, with the intended weight buffer.
Another friend had the same issue, and mic'ed the V7 inconel tube. It measured an ID slightly smaller than mil-spec.
This is something t o keep in mind if you have a properly gassed gun, like a Hodge or Centurion.
I know this is a bit of a necropost, but...
I have owned a rifle since 2015 that took WAY lighter a buffer than it should have, to run. A V7 Inconel gas tube was installed from the word "go". No binding. No patency issues. No fitment problems.
Finally, I removed said tube, and installed a microbest (Daniel Defense). The gun immediately began cycling the way it was intended, with the intended weight buffer.
Another friend had the same issue, and mic'ed the V7 inconel tube. It measured an ID slightly smaller than mil-spec.
This is something t o keep in mind if you have a properly gassed gun, like a Hodge or Centurion.
Great info, actually answers a question I had and is going to have me swap gas tubes on two different rifles.
vicious_cb
01-17-20, 19:38
I know this is a bit of a necropost, but...
I have owned a rifle since 2015 that took WAY lighter a buffer than it should have, to run. A V7 Inconel gas tube was installed from the word "go". No binding. No patency issues. No fitment problems.
Finally, I removed said tube, and installed a microbest (Daniel Defense). The gun immediately began cycling the way it was intended, with the intended weight buffer.
Another friend had the same issue, and mic'ed the V7 inconel tube. It measured an ID slightly smaller than mil-spec.
This is something t o keep in mind if you have a properly gassed gun, like a Hodge or Centurion.
Glad I didnt go that route. I went with a nitrided gas tube from SIONICS, my Hodge barrel is running everything I feed it with a A5H3.
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