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View Full Version : Chrome vs. Non-chrome lined barrels? Educate me please!


SA227driver
12-19-2011, 7:46 AM
I see different ARs for sale in the store and in the forums here all with different barrels, but the one commonality is that the chrome lined barrel ARs always seem to be more expensive.

Is the chrome to help with longevity of the barrel?
Better rifling?

Advantage/disadvantage to either one?
Shorter barrel life with a non-chrome barrel?

Can the AR "gurus" jump and school an AR newbie about the difference?

Thanks ahead of time.

berg
12-19-2011, 8:06 AM
Adding the chrome is an extra step in the manufacturing process so it adds to the cost.

Chrome is very hard so it extends the life of the barrel, plus it's smoother so it's easier to clean.

Some people claim non-chrome barrels are more accurate but I suspect that's only noticeable if you are using match ammo under match conditions with an accurized rifle.

-hanko
12-19-2011, 8:16 AM
Adding the chrome is an extra step in the manufacturing process so it adds to the cost.

Chrome is very hard so it extends the life of the barrel, plus it's smoother so it's easier to clean.

Some people claim non-chrome barrels are more accurate but I suspect that's only noticeable if you are using match ammo under match conditions with an accurized rifle.
...and you are a shooter capable of match grade accuracy;).

-hanko

starsnuffer
12-19-2011, 9:56 AM
Chrome lining covers a lot of poor manufacturing issues with the barrel itself, making a better barrel for most uses. It's a very old technique, and found its way into "mil-spec" doctrine around the time the M16 was having all sorts of corrosion and jamming issues due to old/out of spec ammo. Ever since then "chrome lining" has been a mil-spec buzzword and mandatory for military weapons, even though the benefits are dubious and there are much better modern solutions to the same problem. As you know, "milspec" sells guns to mall ninjas, and gun makers make guns so they can sell them.

A chrome lined barrel is only as good as the chrome lining itself. As the chrome wears, chips, flakes, and scratches, the barrel becomes less accurate. A non-lined barrel can be made to be much more accurate over a much longer time frame, however, non-lined barrels do take an extra swab or two to clean. There are also more modern barrel treatments that penetrate the metal much deeper that offer the same benefits of chrome, without the flaking/chipping issues chrome presents.

-W

Curley Red
12-19-2011, 10:16 AM
There are also more modern barrel treatments that penetrate the metal much deeper that offer the same benefits of chrome, without the flaking/chipping issues chrome presents.

-W

Can you mention what these other options are for those of us that are in the market for a barrel and would like other options other than chrome.

icenix
12-19-2011, 10:55 AM
A chrome lined barrel is only as good as the chrome lining itself. As the chrome wears, chips, flakes, and scratches, the barrel becomes less accurate. A non-lined barrel can be made to be much more accurate over a much longer time frame, however, non-lined barrels do take an extra swab or two to clean. There are also more modern barrel treatments that penetrate the metal much deeper that offer the same benefits of chrome, without the flaking/chipping issues chrome presents.

-W

And how many rounds are you talking before you start to see flaking, chipping, etc.?

Dave07997S
12-19-2011, 11:35 AM
Chrome lining covers a lot of poor manufacturing issues with the barrel itself, making a better barrel for most uses. It's a very old technique, and found its way into "mil-spec" doctrine around the time the M16 was having all sorts of corrosion and jamming issues due to old/out of spec ammo. Ever since then "chrome lining" has been a mil-spec buzzword and mandatory for military weapons, even though the benefits are dubious and there are much better modern solutions to the same problem. As you know, "milspec" sells guns to mall ninjas, and gun makers make guns so they can sell them.

A chrome lined barrel is only as good as the chrome lining itself. As the chrome wears, chips, flakes, and scratches, the barrel becomes less accurate. A non-lined barrel can be made to be much more accurate over a much longer time frame, however, non-lined barrels do take an extra swab or two to clean. There are also more modern barrel treatments that penetrate the metal much deeper that offer the same benefits of chrome, without the flaking/chipping issues chrome presents.

-W

This was common when militarizing a weapon, why it didn't happen with the M16 initially is another smack at the McNamara era defense department. Especially for a rifle that is on its way to the jungle enviroment of Vietnam.



Dave

m03
12-19-2011, 11:41 AM
And how many rounds are you talking before you start to see flaking, chipping, etc.?

This may or may not apply to ARs, but from personal experience, I put somewhere in the neighborhood of 4,000 rounds through an AK with a chromed-lined barrel and never saw any evidence of such wear. I was the second owner too, and I would guess that the rifle had at least 2,000 or more rounds through it before I got it. It was well maintained though.

Lon Moer
12-19-2011, 12:20 PM
The chrome-lining is really only applicable if you are jumping into the ocean, crawling across the beach and wading through jungle swamps. Otherwise it is just another feel good option, like putting some fancy wheels on your car.

Now I have no problems with a chrome-lined barrel, and have several AR's that have them, but there are literally hundreds of thousands of AR's in use without chrome-lined barrels that function just fine.
:)

starsnuffer
12-19-2011, 12:27 PM
Can you mention what these other options are for those of us that are in the market for a barrel and would like other options other than chrome.

Case hardening techniques, mostly. You may have seen the recent thread here about Melonite and other nitrocarburizing procedures. Even cold forging produces barrels much harder then the poorly machined barrels chrome lining was designed to "fix".

Here's a link to some info:http://burlingtoneng.com/case_hardening.html

As to the "when do chrome lined barrels break down" question, it's not easy to answer. Usually neglect, poor maintenance techniques, or just sheer bad luck cause the chrome to flake or chip, and once it does it continues to flake and chip. If the chrome stays in tact, the barrel will last a very long time.

-W

RookieShooter
12-19-2011, 12:32 PM
What about Stainless steel barrel vs chrome barrel?

Nathan Krynn
12-19-2011, 12:36 PM
Chrome lining extends life but "may" decrease accuracy. There are more benefits but that is the basics.

I say may as you will probably not ever tell the difference unless you are a high power/service rifle shooter at 1k.

I have a dez arm 1/9 barrel that I lost count at 6.5k rounds on it, this is the beater rifle that is a hodge podge of stuff on it that I use for the local match's. I do this to show that it is the shooter most of the time vs the high dollar equipment. Last months carbine local match we had a 50 yard group 10 round 2 min stage. I won this stage in my squad by a mile with 45 seconds left.

If it is not a select fire and not going into a jungle or on a boat then you don't "need" it. Remember that the krag-jorgensen, 03 Springfield, m1 carbine, and the m1 garand all did not have chrome lining and ran in plenty of jungles (the krag-jorgensen didn't run fine but that wasn't due to not chromed lined).

m03
12-19-2011, 12:41 PM
The chrome-lining is really only applicable if you are jumping into the ocean, crawling across the beach and wading through jungle swamps.

...or shooting corrosive ammunition, which is considerably more likely to happen to most of us here than the above scenarios :)

bwiese
12-19-2011, 12:46 PM
And how many rounds are you talking before you start to see flaking, chipping, etc.?

A proper QUALITY chrome-lined barrel should never see flaking/chipping outside of chamber erosion zone - and even then, this zone should just be a 'wear zone'.

Good chrome-lined barrels are based on good barrels to begin with and the chrome lining was designed to impart protective abilities as opposed to patching some barrel imperfections.

Accuracy of chrome-lined barrels is really a function of reject rate vs. spec. There's usu a 30+% reject rate - out-of-round chamber defects, bore too tight, etc. Different companies have different specs. Colt M4A1 HBAR barrels have a very very good reputation for accuracy and folks are making 400-500 yd shots in Afghanistan w/4X ACOG and 77gr OTM ammo. FN makes their "SPR" 308 bolt gun (rough equivalent in purpose/form-factor to a Rem. 700PSS) with a chrome-lined barrel and it's renowned a same-hole shooter.

No other barrel coating process has been in circulation as long nor tested as well. Lotsa small-fry low-volume mfgrs make claims, but until Uncle Sugar tests & orders, chrome lining still owns the day. (And it's not about cost: chrome lining may cost more than other claimed equivalents esp today with all the enviro regulatory oversight on chrome processing...)

wash
12-19-2011, 1:00 PM
Chrome hate?

When chrome is done right it makes a barrel that will sustain lots of abuse. You don't have to clean it often unless you want match grade accuracy and if you want that you probably aren't going chrome for other reasons.

If your chrome flakes, you either got bad chrome or you've gone through thousands and thousands of rounds. I would be disappointed if I saw chrome flaking before the 10,000 round point. After that I would be mildly annoyed and swap out the barrel.

For a gun that you want to go bang every time but you don't want to spend a lot of time maintaining, you can't do much better than a chrome lined barrel.

I havent tried nitro-carburized stainless barrels but that is on my list. It's supposed to have similar wear and corrosion resistance with perhaps better accuracy potential. We'll see.

Richard Erichsen
12-19-2011, 5:24 PM
I see different ARs for sale in the store and in the forums here all with different barrels, but the one commonality is that the chrome lined barrel ARs always seem to be more expensive.

Is the chrome to help with longevity of the barrel?
Better rifling?

Advantage/disadvantage to either one?
Shorter barrel life with a non-chrome barrel?

Can the AR "gurus" jump and school an AR newbie about the difference?

Thanks ahead of time.

Not really an AR specific topic, this comes up a lot for military arms in general. The reason chrome is in there is because most world military organizations decided that bores needed a degree of environmental protection, corrosion protection (particularly important when corrosive primed ammunition was the norm) and improved wear and thermal resistance to preserve the chamber throat area, muzzle crown and the edges of the rifling grooves as long as possible. In general hard chrome lining increases barrel life by about 2.5-3 times, but there is no such thing as a free lunch.

The reason most target rifles don't have the chrome lining is because depositing a completely consistent thickness of chromium across the entire bore is neigh impossible, which degrades accuracy, if only slightly. To make a barrel which is to be chrome lined, the barrel manufacturer will cut the final bore dimension oversized by a few thousandths and built up to the desired bore diameter from the buildup of the chrome during the plating process. Target rifles use very precisely manufactured barrels that cost hundreds of dollars just for the unfinished blank, given how these barrels are used, an unlined barrel (usually stainless, sometimes nitrided/nitrocarburized) is preferred.

Hunting rifle barrels traditionally are not lined, not so much because pin point accuracy is needed (4-6MOA is good enough to take any large game at typical hunting ranges which tend to be less than 400-500 yards), but because the chrome isn't really needed on a rifle that might not even fire 100 rounds in a given year and then be put in a safe or gun cabinet. Even in wet or humid conditions (Oregon/Washington, Louisiana/Mississippi comes to mind), a well cared for rifle that is cleaned and oiled will do fine without chrome lining. Unlike a soldier deployed to the field, a sportsman can generally stop to clean and oil their weapon whenever they need to. Despite the lack of chrome lining, many fine sporting rifles built in the later part of the 19th century remain serviceable to this day.

Many AR makers use barrels built according to a milspec or are based on one. The M16 and M4 milspec calls for a chrome lining and given the shared components often used, sometimes as a selling point, the bulk of the AR15 barrels also have chrome lined barrels. For a civilian shooter who will likely lavish a great deal of attention to cleaning their weapon every time they fire it, an unlined barrel will last longer than many components of the AR15 platform will last. At 6000-7000 rounds, a typical unlined barrel useful life (they still shoot, but their accuracy declines from erosion at the chamber throat and muzzle crown, more so than the rifling or bore), many other parts of the rifle will also have to be replaced. At current avg. ammunition prices, you'll have fired about $2500 worth of ammo through the rifle by the time the rifle is do for overhaul, of which the barrel will be just one component to be replaced. With nitrocarburizing (melonite) the useful life before accuracy degrades to an unacceptable level is about 3 times higher than the unlined barrel, or about $7500 in ammunition at avg. ammo prices. Hard chrome lining will be similar. Practically speaking, most folks don't burn through $2500 of ammo on a single firearm very quickly. My regular range visits are under 250 rounds per trip (I can only shoot one at a time) for any two or three rifles I might take with me to the range. Assuming just two weapons are taken and firing 125 rounds per weapon, with me going to the range about once a month, it will take me a year to fire 1500 rounds or about 4.6 years before the barrel deteriorates to the point that it needs to be replaced and my bolt group, buffer/action spring and/or gas system components need overhaul. Most owners aren't even firing 125 rounds a month through their rifles, it might only be a couple of hundred in a year with sporadic time at the range as time and their attention span allows. At 250 rounds per year, it would take over 20 years to reach 5000 rounds, the point at which many components in the AR15 should be serviced and the barrel might still have another 2000 rounds to go before it is degraded enough to bother replacing it.

If this were a full auto weapon, I'd say go for it and get the cold hammer forged, chrome lined 4150 CM barrel and upgrade your bolt group accordingly. Few of us are authorized to enjoy burning through thousands of rounds on full auto in a single afternoon. If you are someone who can, then the cost of ammo will be your biggest concern because the cost of frequent rifle component replacements to keep your F/A weapon going will be a drop in the bucket by comparison. If you reach 6000 rounds of use in a single week, the last thing you'll need to worry about is how much a new barrel costs.

Don't get too excited about all the how-great-is-chrome or the superiority of melonite or some new barrel material that just came down in price (Inconel and other high temperature "super alloys" that are about as necessary on a semi-auto rifle as my lawnmower has need of mammary glands), think of the rifle as a whole and how you plan to use it (and where). If you aren't planning, or don't expect to shoot your rifle very much, you don't get a star on your chart for spending the most money to get 250-500 rounds down range in a year. If in the fullness of time you burn through a barrel and various other parts, by all means, step up to the barrel upgrade path which is available to you. Given the increasing cost of ammo, put your money where it counts. A rifle with no ammo is no fun at all. If you really want to, you can spend a bit of money to get the barrel melonite treated and extend it's life if you find you have a good, tight and accurate barrel. Broken in the melonite will do the most good, whereas a brand new barrel will take a lot longer to break in with a tough case hardened shell over the slightly rough chamber throat area that breaking in attempts to smooth out. The ability to do this is unique if generally overkill for most shooters, because as mentioned, with chrome you have to manufacture the barrel specifically for the lining or the bore will be undersize (too tight) in a barrel's bore originally designed to be unlined.

R

HK Dave
12-19-2011, 5:31 PM
^ +1

Most people won't shoot enough to see the advantage of a chrome lined barrel.

If one is really shooting that much ammo, the barrel is the cheapest part of the equation, chrome lined or not.

Drivedabizness
12-19-2011, 9:24 PM
Not to thread jack but I've seen so much (conflicting) opinion...

How do you "break-in" a barrel???? Mine is melonite and I get to pick it up in less than 43 hours!

five.five-six
12-19-2011, 9:29 PM
The chrome-lining is really only applicable if you are jumping into the ocean, crawling across the beach and wading through jungle swamps. Otherwise it is just another feel good option, like putting some fancy wheels on your car.
:)

or shooting corrosive ammo

bwiese
12-20-2011, 12:25 AM
Remember chrome lined barrels come with chrome lined CHAMBERS.

Of the melange of ARs having problems that I've helped folks out with, most did not have chromed barrels/chambers - and this really helps with the extraction/ejection process. Rough/nonslick chambers just aren't as good.

m03
12-20-2011, 12:31 AM
or shooting corrosive ammo

Damn, there's an echo in here...


:)

Gnome
12-20-2011, 1:23 AM
A proper QUALITY chrome-lined barrel should never see flaking/chipping outside of chamber erosion zone - and even then, this zone should just be a 'wear zone'.

Good chrome-lined barrels are based on good barrels to begin with and the chrome lining was designed to impart protective abilities as opposed to patching some barrel imperfections.



How does one know who makes a quality chrome-lined barrel? Are we to assume that all major manufacturers (RRA, BCM, Noveske, Stag, CMMG, Spikes) are safe?

Richard Erichsen
12-20-2011, 5:05 AM
Not to thread jack but I've seen so much (conflicting) opinion...

How do you "break-in" a barrel???? Mine is melonite and I get to pick it up in less than 43 hours!

Depending on the manufacturer (and they vary a lot in opinions), there could be a requirement to fire a few shots, run wet patches until the streaks are gone, then dry patch until swabbed clean/dry and fire again. The bore of a melonite or chrome lined barrel isn't going to change much in many thousands of rounds, it's as hard or harder than a mill file. For a melonite treated barrel, the outer and inner surfaces reach 60-64 HRC for chrome moly barrels and 70-72 HRC for stainless barrels. Compare this to hard chrome lining which is in the 70 HRC range. On quality barrels, the chamber and throat area will be reamed to a a fairly good finish, but are very hard to polish where throat intersects with the grooves and lands. There is a pattern, like a fine file, that cuts across the grooves and lands. It is this interface that is where the attention needs to go and where most of the "break in" is actually happening when barrels are otherwise of the high cost, double-hand lapped target barrel types.

When you fire a shot, the high pressures and temperatures are creating a gas plasma, essentially vaporizing any bur standing up from the throat surface. Jacket material is also vaporized at this location and the combo of both types of metal (a tiny bit of steel and a larger amount of copper) are what you are trying to clean away. Each round fired is doing a tiny amount of burnishing and "fire polishing" of sorts. The small amount of steel that is burned away won't tend to stick anywhere else, but the copper jacket material can depending on finish and alloy - it doesn't stick to QPQ treated barrels, chrome lining or stainless steel very well which is why these materials are sometimes preferred. Left unchecked the copper can add an inconsistent thickness of deposits that vary the bore diameter (if slightly). Barrel makers know which barrels, based on alloy or process will tend to have a greater affinity for copper and which will tend to have less. If they published too many different (conflicting) instructions customers would get confused and run up the phone bill or tie up the lines in their technical support teams, so one set of instructions that work for all their barrels is generally what they will provide in order to avoid much of the confusion.

The second school of thought is just shoot it and inspect the bore for signs of copper fouling and clean as needed. I tend to agree with that, but I'm not trying to win a trophy for best long range shot, where there is a great deal of mystery and sorcery involved in some folks methods, both rifle builders and shooters alike.

R

Richard Erichsen
12-20-2011, 5:08 AM
Remember chrome lined barrels come with chrome lined CHAMBERS.

Of the melange of ARs having problems that I've helped folks out with, most did not have chromed barrels/chambers - and this really helps with the extraction/ejection process. Rough/nonslick chambers just aren't as good.

Any chamber can be polished to some degree, but if the chamber wasn't reamed properly then the chrome lined chamber will just seal the roughness behind a hard layer that you can't do much with.

R

Richard Erichsen
12-20-2011, 5:12 AM
How does one know who makes a quality chrome-lined barrel? Are we to assume that all major manufacturers (RRA, BCM, Noveske, Stag, CMMG, Spikes) are safe?

Even a good manufacturer can have a bad batch, but fortunately this isn't a safety issue as much as it is a warranty issue. Your barrel won't explode if a thin layer of chrome did manage to dislodge, though your accuracy might suffer. If the chrome flakes, cracks or chips, what are the terms of your warranty for your barrel or rifle and how quickly can you get a replacement for it?

I wouldn't worry too much about chrome lining peeling off on a new barrel after only a few hundred rounds, there doesn't seem to be much track record of that on ANY military barrel used on any number of military arms made over the course of many many decades.

R

Richard Erichsen
01-21-2012, 6:25 AM
Not to thread jack but I've seen so much (conflicting) opinion...

How do you "break-in" a barrel???? Mine is melonite and I get to pick it up in less than 43 hours!

Unless otherwise advised by your barrel manufacturer - just shoot it and clean it when you're done. Some barrels have an affinity for copper which is one of the items barrel break-in attempts to prevent from accumulating, but the QPQ process makes the chamber and bore much smoother and less prone to these problems such that you really don't need to do anything for them beyond normal cleaning.

R

Richard Erichsen
01-21-2012, 6:28 AM
How does one know who makes a quality chrome-lined barrel? Are we to assume that all major manufacturers (RRA, BCM, Noveske, Stag, CMMG, Spikes) are safe?

Feedback from owners of the products from any manufacturer should be all you need. I never really listen to write ups or reviews from the "professionals" alone because there are often advertising dollars attached to many reviews.

R