Barrel Material ?s

[ADIDAS69]

Imagine two barrels of exact same dimensions one stainless steel (assume best type for barrels) and one chrome molly or what have you. I know the none stainless will likely last longer; in terms of accuracy at the start is one more accurate than the other. I heard someone suggest that stainless is somehow inherently more accurate but that doesn't seem right.

[ballardw]

I believe you want a more complete metallurgic analysis than simply "stainless". There are many steels even within the stainless designation. I suspect some would be completely unsuitable for barrels (subject to erosion and wear) and other issues depending on series.

And the material is not the only consideration, heat treat, machining, mounting ....

So any assumption or statement that "stainless" is better/worse than "chrome moly"(again an entire class of steels) nees some serious support.

I could see the accuracy statement coming if 1) all of the stainless barrels I had used were intended for match and 2) the chrome-moly weren't.

[mete]

Crucible makes a stainless specifically for rifle barrels - 416 R . A few other types of stainless are also used .
Cro-moly is basically 4140 which is a very useful alloy for many things and 4150 is also used .
Specific composition varies as does heat treat etc.
Longer life for a barrel is mostly letting the barrel cool between shots !
Some makers cryogenically cool the barrel during processing but others have found no advantage .
As a metallurgist I have found much of cryo is hype , sad to say. It's better use is with high tech steels and can be found in some of the better knives ! Such as those made with Crucibles CPM process.

[Jim Watson]

Once upon a time, CM was preferred for barrels because the stainless of the day was not very machinable and the bores were not as smooth.
Now with the alloy fudged to 416R it is possible to make better bores and the chromium content reduces erosion. Note that most target rifle barrels are now stainless.

Other alloys are or have been used. Type 410 SS may be somewhat better than 416R but it seems to have dropped out of the catalogs. I have a pistol barrel made out of 17-4 PH, but its manufacturer has gone to 416R.

On the other hand, Fred Kart, who makes one of the better 1911 pistol barrels on the market, says "stainless is for cookpots." He seems to be alone in that preference, but his barrels are first class.

[ShootistPRS]

Stainless alloys come in all flavors and are typically tailored for the specific use. Most "cook pots" use a 3xx stainless to protect from corrosion while most knives use 4xx series stainless for better edge holding. There are very hard stainless alloys used to make ball bearings (BG-42) and an alloy that was used yo make knives but isn't used much because it is very and takes a lot of work to put an edge on. (ATS-34)

So when talking about stainless alloys, without reference to the specific alloy and the heat-treating process, you really can't make any judgment to its ability to withstand wear, erosion or corrosion.

[mete]

Those of us who are metallurgists try to be specific , others may not understand the need . I remember seeing barrel blanks made of 41R40 a long time ago .They were from WWII and the R is re-sulfurized ,extra sulfur for easier machining . Yet I don't ever remember that designation today .416 stainless is just 410 with high sulfur ! Crucible's 416 R is just a carefully formulated version especially for barrels !

Cook pots ?? Which ones ?? Be specific ! They used to be 300 series SS ,often listed as 18-8.But then they started to use induction stoves which require magnetic type SS , 300 series is non-magnetic . So the pots which can be used with induction ,the better ones state that, are 400 series or other magnetic alloys .! Today's lesson in metallurgy !!

[Nathan]

Thr 416R barrel should be a better choice for pure accuracy, if machined for that. It would also be more corrosion resistant. It would not last long under heavy fire.

A 4140 barrel would be pretty similar, but less corrosion resistant. My understanding is 4150 would hold up better to sustained fire better.

[HiBC]

I'm sure I do not have the answer.

I would suppose if you got the top barrelmakers together over an "iced tea" for a discussion on the subject it would be interesting...and there would be differences of opinion.

Then have another discussion with benchresters and another with theArmy Marksmanship Unit,....I do not think everyone would agree.

You might want to distinguish between cut rifled,button rifled,hammer forged,etc. Debate continues about which is best,and steel characteristics for button rifling are not the same as for cut.

One more thing the metallurgists can explain better...

The additives to improve machinability(surface finish) are generally detrimental to barrel life.
And to a degree,by more time,effort,scrap rate,etc (cost) a better barrel CAN be made out of tougher to machine steels,AND you will pay.
Then there is the problem of sourcing barrel quality steel...
Made from coal mines,Iron mines,steel mills.... where are those?

[ShootistPRS]

Bar One makes barrel steel in a number of different alloys.

[ADIDAS69]

My first AR10 is a DPMS LR308 24" stainless it has served very well for thus far about 6000 rounds. My groups are starting to open up which may be the barrel or me or both; I'm 13 years older than when I purchased it. From what you've all said it sounds like a chrome lined chrome-moly barrel would be as suitable a replacement as any stainless of highest possible quality.

Next question, do I get an M118LR chamber?