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Is stainless steel hard enough for gun barrels?

(2003)

Q. To whom it may concern,

I did not know whom to ask so I hope that I am not wasting your time but how hard is stainless steel? In particular, a shooter friend of mine says that stainless steel rifle barrels will outwear normal moly steel barrels. Is that true? Another friend says the exact opposite. I know that stainless is easier to keep clean and resists rust rather well BUT will a rifle barrel last longer from the wear and tear of shooting if it is stainless, or is stainless steel in this application a little softer than a normal barrel? I did not know who else to ask.

I thank you in advance for you time and for helping me with my query.

Marco Rusterholz
- Karoola, Tasmania, Australia


(2003)

A. Either will last thousands or tens of thousands of rounds. The final answer is - it depends. The exact alloy and who manufactured it will be the determining factors in the answer. Both are fine, if bought from a reputable manufacturer. Most people do not want a bright reflective barrel for normal, non marine, hunting.

James Watts
- Navarre, Florida

misc. plating stuff
For Sale cheap




(2003)

A. Hello Marco!

The trouble is that there are so many stainless steels, coming in a variety of hardness ranges after heat treatment (anywhere from Rockwell C 20 to 60) that I can't make a blanket statement about one or the other lasting longer. I'd also GUESS that it can depend on how the gun is designed, and used. If the main wear mechanism is oxidation wearing away, then it makes sense that stainless would be preferable. Yet if the problem is the bullets galling & scoring the ID of the metal barrel, then the alloy steel barrel should be the better choice.

A lot of my co-workers complain that I never answer THEIR questions, either.

For more information on stainless steels, I recommend Atlas Steel of Australia's site, at http://www.atlas-steels.com.au/technical_info.html^http://www.atlassteels.com.au/site/pages/technical-library.php. For more discussion on the topic of gunsmithing, I'd recommend the newsgroup rec.crafts.metalworking^https://groups.google.com/forum/?fromgroups=#!forum/rec.crafts.metalworking.

Good luck!

Lee Gearhart
metallurgist
East Aurora, New York

----
Ed. note, March 2013:
Atlas Steels URL has been updated, and a "google groups" link to rec.crafts.metalworking has been added since few readers remember how to use newsreader software . . .
. . . but you will appreciate monitored forums like finishing.com after you see what happened to the open newsgroups :-)


(2003)

A. How much time do you have? Your question is extremely open ended and there are huge text books about the answer. At the risk of being accused of being rude, may I suggest you look in a text book about the properties of stainless steel, as it will give you everything you need to know. However, just to generalize, it is usually true that for a given stainless steel composition, the presence of molybdenum will let it be hardened to a greater extent than if moly wasn't there. Whether a stainless steel barrel will last longer than a non-stainless barrel, I cannot answer, but I would expect both to last for many thousands of rounds if they are both well treated and not abused. Given the choice, I would go for the moly addition if I had to rely on the gun for my life! Secondly, there are hundreds of types of stainless steels, as it is a generic name for an iron-chromium alloy that has at least 12% chromium to give it some anti-rusting properties. The most common stainless steels are the 300 series which cannot be heat treated but can be work hardened. These are mixtures of iron, chromium and nickel, often with other goodies thrown in for specific reasons. Generally these have hardnesses of about 180-220 Vickers (Hv) or 184-210 Brinell. Cold working can increase their hardness to almost 400 Vickers. Other stainlesses have very little or no nickel in them, these are most commonly 400 series stainlesses and can be heat treated as well as work hardened. These steels have hardnesses between 200 and 650 Vickers (or 210 to 550 Brinell). Furthermore, there are the more esoteric stainlesses that go under the 600 series; these are serious metals with specific and usually expensive applications, such as in jet engines. On top of this is a range of precipitation hardeneable steels that are usually identified as 17-7 PH or something similar. These can be very hard, going up to Brinell values of 600+. I hope this sheds some light on your question.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


(2003)

thumbsup2Thank you all very much for what you have stated to me thus far. I guess I should be a tad more specific with my question. I realize that there are many variants of either stainless steel rifle barrels as well as Moly steel rifle barrels. A particular manufacturer of rifle barrels in Australia has said ... "We use 416 for our stainless barrels and 4140 for chrome moly. These are world-wide industry standards, and though the composition and hardness may change within parameters, the basic steel remains the same. 416 is easier to machine than 4140, but that doesn't mean it will wear faster. It is simply not possible to say one will last longer than the other."

Now I would have thought that steel which is easier to machine would also be softer but the company says elsewise. Fair enough. For me, the issue is not about how easy a rifle is to clean. It is about longevity. If I use typical factory ammunition in my Moly steel barrel, say 4140, will it outlast the 416 stainless barrel by standing up to the friction and wear each bullet exerts to the barrel each time it is fired?

I realize, gentlemen, that there are many variables in steel manufacturing thus why I have tried to emphasize some of the factors that I face. I really do appreciate your time in this matter.

Marco Rusterholz
- Karoola, Tasmania, Australia


(2003)

A. I think that your problem is trying to relate hardness to wearability. While it is a factor, it is not the only one. I will take a little issue with 416 being softer than 4140. That depends on the heat treatment state. In the fully annealed state, there is not enough difference to talk about. It may require slightly different parameters for the machining, but both are very easy to machine. To only consider the friction wear on a barrel is incomplete. The chemical reaction from different powders has to be brought into consideration. Then the bullet itself affects the wear. Antimony hardened, dead soft lead, full metal jacket, silver points or ?. Each factor will have a minor effect. Finally, either one is probably good for over 10,000 rounds. I have two .22 cal rifles (pump)that are just under 100 years old, both are in rough shape, but both are very accurate for that type of weapon. The 96 year old one has had well over 3,000 rounds put thru it by me and I am the third owner of it.

James Watts
- Navarre, Florida

misc. plating stuff
For Sale cheap




(2004)

Q. Sorry I'm tardy getting into this thread. Lothar Walther GmbH is a German rifle barrel maker who claims a proprietary barrel steel LW-50, or LW 50, or Lothar Walther 50 is a significant improvement over 416R/416BQ stainless rifle steels. The superiority pertains to corrosion resistance and accurate barrel life.

I have tried to identify the steel's chemistry, or find a quantitative analysis of it with 416R/416BQ and 17-4PH steels. Nothing found. I cannot cross reference the proprietary name with German DIN/WN indices, so I'm putting the query out. My particular interest pertains to corrosion resistance to products of black powder combustion.

Lance Klein
- Fort Myers, Florida


(2004)

A. Hi Lance. Lothar Walther 50 could be worlds better, but suppose it is: they own the name so they can put it on a different process tomorrow. Auto makers do that perennially: a particular model name is their top-of-the-line super luxury car one year, and within a few years that model name has been gradually moved downscale until it's put on their cheapest fleet machine. A Ford Thunderbird was a 2-seat sports car, then a 4-seat luxury car, then a 6-seat family car, and now it's back to being a 2-seater again.

So if you are a researcher, how can you test a steel that goes by a trade name, and put your name on a report that says it's good it -- knowing you have no control over what process will go by that trade name next week? What I'm saying (with so much wind) is that it doesn't surprise me that you couldn't cross-ref it, and I don't think anyone else can or should. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey

(2004)

A. Check out the informative article at; http://www.riflebarrels.com/articles/barrel_making/details_of_accuracy.htm This article does touch on the most significant area pertinent to the question of barrel life (in most cases), i.e., throat erosion.

Cheers,

Matt Naumann
- Tom Price, WA, Australia


(2005)

A. To understand this subject, one must understand high-strength steel. For the record, I am a metallurgist by trade, and heat treat Quality Manager so I know enough about these steels. I do not like AISI 416 SS for gun barrels and I will explain why:

To achieve the high strength the steel must possess to withstand the forces produced during firing, AISI 416 SS and/or AISI 4140/4150/4340 must be austenitized, quenched and tempered. After quenching, the average 416 SS will be about 40 Hardness Rockwell C (HRC) and 4000 grades about 50 HRC (To benefit those who do not know this scale, a file will be about 60 HRC, and a hammer will be about 30 HRC). In the "as quenched" state, the material is brittle and unstable. Tempering is employed to reduce the hardness to a "tough" state and stabilize the newly formed martensitic structure. In the case of 416 SS, and to get the hardness to about HRC 30 so it is able to be machined, one must temper at about 1075 °F. This is not desirable as 416 SS shows a marked reduction in impact resistance when tempered between 700 °F and 1100 °F (temper embrittlement). It will also show a marked decrease in corrosion resistance. 416 SS does still, however, exhibit better wear characteristics and corrosion resistance than the 4000 series high-strength grades mostly due to the higher chromium content. It is also readily available, inexpensive, and it looks good so manufacturers use it. The big problem though is that it is not as free-machining as the 4000 series grades so generally sulphur is added to alleviate that problem. What you then have is a microstructure with "sulphide stringers" in it that has been tempered in a bad tempering range so the impact resistance of the steel is very poor. Failures happen, and are not really wide-spread, but I will not buy a 416 SS barrel for that reason. The AISI 4140/4150/4340 grades do not have this temper embrittlement problem, and show superior impact resistance when tempered to about 30 HRC. They are cheaper to buy in a production rifle. One who takes good care of a firearm will never have any major corrosion and wear issues with the 4000 grade steel barrels anyway. And if you do use it an awful lot and it begins to wear out, well then you got your money's worth from the product, just buy a new barrel. Nothing lasts forever anyway. As a note, AISI 410 SS is a better alternative to 416 SS as is does not generally have the sulphur issue, however the temper embrittlement issue is still a concern.

Here is my opinion: Unless you are competition shooter, buy the non-stainless grade barrels. If you are a professional match shooter find a good AISI 17-4PH barrel as it is a much better choice if one wants corrosion resistance, wear resistance, and impact resistance.

For my money and safety, it is a 4000-series material.

Respectfully submitted, Mike M.

Michael Moyer
- Green Lane, Pennsylvania


April 13, 2010

A. Rifle barrels for the greater part don't wear out, the throat of the rifle, that first part of the rifling immediately in front to the cartridge case is in a liquid state at the moment of firing, this film of molten metal is very thin but it exists none the less. The larger the powder charge combined with a smaller bore greatly accelerates the erosion process, the surface of the throat as it is called is literally sandblasted by powder particles, some of these cartridges e.g. the 6.5 Winchester Magnum is said to erode a barrel out in as few as 800 rounds, whilst a 308 Winchester is generally good for 10,000 rounds before being converted into someone's sporting rifle, Most big bore shooters opt for stainless for its erosion resistance and ease of cleaning and I doubt if anyone keeps records so detailed as to draw a comparison between the two. I think either barrel is as good as the other taking into account personal preferences and budget limitations, you cannot easily blue stainless and it looks out of place on some rifles but for my money I will use whatever is available at the right price,
PS: I have fitted enough to know what I am talking about.

Vaughn Gunthorpe
- Townsville Qld Australia


April 24, 2011

thumbsup2 Thanks to all who have helped with the info over the years lol. It seems to me that both kinds of steel can be machined (Button rifled) in whatever fashion to exacting tolerances. It seems also that stainless may resist throat erosion better and in the calibers I was using (6.5 Swede, 300 mag) I tended to run them HOT! So the 416 barrels proved their merit.

Nowadays I have settled down for more 'gentle' barrel pressures. Wear-n-tear wise both seem good with suitable attention paid to barrel cleaning. Stainless may not be as 'strong' but gun barrels don't tend to be used as blunt instruments. Therefore I would suggest that the strength issue pertains more to hard use knives - something I own a lot of and carbon has the edge over stainless there except for perhaps the 'INFI' steel used by the Busse Combat Knife Company. A very unusual proprietary 'stainless' that is legendary strong!

Thanks once again all who submitted info.

Marco

Marco Rrsterholz [returning 8 years later!]
- Launceston, Tasmania, Australia
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