Stainless -vs- Steel Barrels.

[brickhouseblues]

In terms of accuracy and longevity in a combat scenario for an AR-15 platform (does ammo have an impact?)... How does a stainless steel barrel compare to a chrome lined steel barrel?

[Dfariswheel]

A hard chrome lined barrel is superior to stainless steel.

Stainless is superior to standard carbon steel barrels and far more resistant to erosion of the throat, which is why virtually all Match and long range barrels are stainless these days.

However, hard chrome is even more superior and lasts considerably longer. Hard chrome is also easier to clean, fouls less, and is far more resistant to corrosion.
For these reasons, the military use chrome lined barrels.

The only down side to hard chrome is that they are typically "slightly" less accurate then a carbon or stainless barrel.
However, this is not an issue on a service or defense rifle, only on a Match or long range rifle where you're trying to get the last bit of accuracy.
In a standard defense or hunting rifle, any slight loss of accuracy is not noticeable and the benefits of hard chrome far outweigh it.

Due to the much greater benefits of hard chrome, on a non-Match rifle it's hard to justify NOT getting hard chrome.

[MarkCO]

With all due respect, Dfarishwheel's post would have been true for most of the history of the AR-15, but not in the last 10 years or so.

Chrome lined barrels are probably the LEAST desirable currently. There are new rifling patterns (5R and polygonal) and new surface treatments (melonite and others) that provide long life and long wear resistance. Also, our powder and primers are much better and much less corrosive pretty much eliminating the original reason for the chrome lining. The only benefit of chrome lined barrels is that they are cheaper. The base metal is typically not as good and the chrome lining process is cheaper.

Thickness build coatings, such as chrome, accentuate the metal imperfections and in many cases, the chrome lining starts to wear/tear/flake off in as little as a few thousand rounds. Spend a little time cutting and comparing barrels under the SEM and you start to see the issues. Shooting a chrome lined barrel to 30K will and a stainless barrel to 30K, in most cases have about equivalent groups sizes and hogged out throats and gas ports.

The only time I will use a Chrome lined barrel is for a cheap closet gun that won't be shot much and likely not maintained. Stainless is better for so many reasons and hardening surface treatments are yet a step or two better yet.

[brickhouseblues]

Very interesting. I need to do more research. I own a SS barrel on my rifle and like it just fine.

[geetarman]

I have SS on a couple of rifles, DPMS, M1A. They seem to be fine. I had a regular steel barrel on a Rem 700 22-250 that I bought new in 1973 or so and replaced it in 2009 with a Douglas SS barrel. I have apparently shot out that barrel in a thousand rounds. I don't load hot. 52 gr SMK and 38 gr. H380. But the barrel is gone.

I have it at the smith now for a new barrel and will be going back to a non SS barrel. I can't say exactly why the barrel went away, but I really do not want another.

[Fishbed77]

For these reasons, the military use chrome lined barrels.

Except on some precision AR-pattern rifles like the SDM-R and Mk. 12 SPR, which use stainless steel barrels to gain the accuracy benefits versus chrome-lined.

[Jimro]

In terms of accuracy and longevity in a combat scenario

In a "combat scenario" chrome lined barrels will last longer, and have better accuracy after you have shot out a stainless barrel. Chrome lined barrels display very uniform accuracy across their useable lifespan, although they are not known for tack driving accuracy.

That being said, I have full confidence in my equipment. And 4 MOA with milspec ammo from a field position is more than enough to get your point across in a "combat scenario" not involving long range sniping.

Jimro

[Skans]

Chrome lined barrels are probably the LEAST desirable currently.

Perhaps, for semi-auto. But, nothing beats a chrome lined barrel for full-auto fire in terms of durability. My dream is to one day find a chrome lined barrel for my AC-556....as of yet, no such creature exists.

[sailskidrive]

Hmmm.... I've heard that a few manufacturers are playing around with Nickel Boron lined barrel, but I haven't seen any barrels offered with it yet.

[ThatBeardedGuy]

To my way of thinking, chrome-lined has been proven for decades in the AR-15 platform. I'm cool with advances in barrel metallurgy but I think I'll stick to what's proven until I see something demonstrably better.

[sailskidrive]

The military has been using nickel boron in the REALLY big barrels for years... Personally, I don't give it much thought.

[dgludwig]

For what it's worth, all of the match configured ARs that I've seen have had s/s barrels. The RRA National Match rifle that I compete with in service rifle matches has a s/s barrel and is more accurate than I can take full advantage of. That said, I have never seen a report testing chrome-lined barrel vs s/s ones, everything else being equal, to affirm that s/s barrels are intrinsically more accurate. If there has been such a comparison (surely there must have been at least one, you'd think), I'd like to see it (them).

[CharlieDeltaJuliet]

MarkCO is right about the newer AR's. that is why you pay extra or the Noveske non chrome lined much barrels and such. Hard chrome lining was used for wear purposes. It prevented wear in the AR's. Companies like Noveske,Hk and others have found out that it can cause inaccuracies when shooting. Hk has proven that with a non lined MR556 it can sustain 15,000+ rounds in one weekend of testing and retain a 1MOA group. I read the write up in one of my AR15 magazines about the new treatment in barrel life and accuracy. Another that is swearing by non chrome lining is S&W. while you can still get the chrome lined, they re using melonite also. It is testing very well also.


But Skans is correct about the fully auto. The military orders chrome lined just because of this. Full auto fire is very hard on barrels.

[Skans]

In terms of accuracy and longevity in a combat scenario for an AR-15 platform

Which are you looking for? Accuracy - then you can find some very accurate stainless barrels;

Longevity/combat scenario with reasonable accuracy? - then you really want a good forged steel chrome-lined barrel/bore of the same make used in full-auto M4's.

I know there are other barrel treatments out there like melonite etc. But, ask if any of these barrel treatments are being used on full-auto weapons.

[CharlieDeltaJuliet]

I guess it's all in the terms of if it is the KAC long range precision or a standard M4.