Importance of chrome lining?

[MTMilitiaman]

I've been noticing a lot of rifles don't come with chrome lining these days. Some of the lower end ARs have the forward assist removed and just the chamber chrome lined, and PTR-91s as well as Springfield Armory M1As don't have chrome lining at all, as far as I am aware. This option used to be a lot more popular. I thought we had pretty much agreed that while you can get away with it on some rifles, on some designs, those that are known to run dirty like the ARs and HK roller locks at least, it was a pretty good idea. I know manufactures are just trying to save some pennies, but it would be nice if you could count on the $1500+ you just dropped into your JLD or Springfield rifle at least got you chrome lining. Am I the only one here who thinks hard use semi-auto rifles should have some friggin chrome in their bores?

 

[kerreckt]

My understanding is that chrome lined barrels are not as accurate. I don't know if this is totally true but my one unscientific test bore (no pun intended) this out. My test was with 2 AR uppers. One had a chrome lined barrel the other was not chrome lined other than that exactly the same. The non-chrome was marginally more accurate.

 

[holdencm9]

That is also my understanding although I have not done any testing...Chrome lined bores are not as accurate, but last longer as they stand up to the heat of sustained fire much better. Probably only an issue with full-auto, or if you fire like 10,000 rounds per year. But if you want "mil-spec" then that's chrome-lined. I think the gun companies are responding to their customers who DON'T run their guns super-hard, and may actually want a more accurate rifle. A lot of the other bore finishes are also pretty good from what I have heard. I still think chrome-lined chamber is key as it aids reliability.

 

[mdauben]

I thought we had pretty much agreed that while you can get away with it on some rifles, on some designs, those that are known to run dirty like the ARs and HK roller locks at least, it was a pretty good idea.

Chrome lining is more an issue for preventing barrel wear than whether or not the gun runs "dirty". Some guns use alternate coating (such as melonite) which can actually offer some advantages over chrome and some simply omit it as a cost saving option. For a shooter who only puts a few hundred rounds a year through a gun, the lack of chrome lining in the barrel will probably never be noticed.

 

[TheCracker]

There is a great documentary on the history m16. It's on YouTube ill see if I can find it in a min.

One point they made was that early m16's in Vietnam hit a terrible rap for reliability because on dirtiness and rust and wear. Chrome lining had been left off to save money but had been recommended.

The gov replaced them w chrome lined versions and trained the troops on maintenance and reliability was much better.

This is mr paraphrasing but what I remember. I studied a lot b4 purchasing my AR And decided the extra 200-300 was defiantly worth it. Even if it cost a tad bit of accuracy.

 

[Bartholomew Roberts]

Based on my experiences, I think chrome lining makes a difference in reliability at the extremes where the rifle is very hot. My unlined SS barrel is more "sticky" when it gets really warm compared to my chrome-lined barrels. Having said that, I've gone 800 rounds in a day with a chrome-lined barrel and 750 in the stainless with no failures to extract from either, so even if my hypothesis is correct, there are very few shooters who will be in circumstances where they notice the difference.

The military studies I've read involved Stellite lined barrels similar to nitrided barrels. They showed slightly better accuracy than chrome-lining but slightly less longevity.

My general opinion is that 90% of the people who buy an AR will never notice he difference between unlined, nitrided, and chrome lined because they will never shoot them in conditions where that difference would be apparent.

 

[TheCracker]

This is defiantly worth the watch.


http://youtu.be/cKBNcq6oAzE

 

[henschman]

The importance of chrome lining depends entirely on the intended use for the rifle.

As has been said multiple times already, hobby shooters who don't run their guns hard and just put a few boxes of ammo through it from the bench a few times a year won't really see any benefit from it. A plain old chrome moly barrel will work fine for their purposes. Since this describes the vast majority of rifle owners in this country, it should be no surprise that so few mfg's offer chrome lining. CL is also not a good feature for guys who are interested in shooting itty bitty groups on paper, or in long range accuracy (they are better served with a good stainless barrel).

But for a hard-use or Second Amendment purpose rifle, for which longevity and reliability while dirty are major concerns, it is a very good idea. For my own use, I consider having either a CL or nitrided barrel a requirement for any sort of fighting rifle (other than a sniper rifle).

I am also disappointed in Springfield for not using CL barrels in their M1As anymore. Of course some will say that our boys fought across Europe and the Pacific with a very similar rifle with just a plain CM barrel... but that's not to say those rifles didn't see a lot of corrosion and pitting, and the rarity of completely numbers matching M1s is a testament to the fact that the vast majority of them had to be re-barreled during their service lives, most of them probably multiple times. And don't forget that those fellows had company armorers fed by the government procurement system keeping their rifles running. Armed citizens do not have that advantage.

For a 2A purpose rifle, at least by my reckoning, the more of a round count you can give it between barrel changes, the better.

I hear a lot of good things about nitrided barrels, as well. By many accounts, they seem to be capable of the same sort of accuracy as a CM or SS barrel, but with the longevity of CL. The technology has been around for a long time, so it's surprising that it is just now starting to catch on. I hope it continues to do so. I'm thinking about putting together an AR carbine with a nitrided barrel from www.ar15performance.com and seeing how I like it. Unfortunately nobody seems to make a nitrided .308 barrel in anything other than 16" or heavy profile, so I will stick with CL for my .30 cal battle rifles.

 

[Bartholomew Roberts]

The interesting question is if you take a stainless match barrel which starts out sub-MOA and is 4 MOA at 300yds after 15,000 rounds and a chrome-lined barrel which starts out 2-3 MOA and after 15,000 round is 4 MOA at 300yds, which barrel actually gave you better service?

That is a question you don't see discussed much because many guys who buy SS match barrels replace them long before they open up to 3 MOA.

It is also relevant to nitrided barrel - if you can start out with the great accuracy some of these S&W barrels are showing AND get 50-75% of the longevity of chrome, you effectively have a barrel that will be more accurate over a longer round count than your typical generic chrome-lined blasting barrel. Of course, all of that depends on your accuracy requirements, how the rifle is shot, etc.

 

[fanchisimo]

Even though I don't shoot a rifle as much as I'd like, I personally would like the barrel to last as long as possible, giving up negligible accuracy, but I mostly just enjoy fun shooting, and paper punching, rather than 300 yd+ shots.

 

[Shear_stress]

I am also disappointed in Springfield for not using CL barrels in their M1As anymore.

If I remember correctly, Springfield's chrome lined barrels were USGI surplus and the supply eventually dried up. It would be nice if they still offered chrome lining on their commercially made barrels, but they probably figure most people wouldn't be willing to spring for it.

 

[hentown]

Chrome is only $40 extra on RRA AR barrels. If you want a match barrel, get a match barrel; if not, get a chrome-lined barrel. Accuracy is a matter of perspective. I've seen two identical Bushy Shorty ARS with chrome-lined 1/9 barrels shoot 1/2" groups @ 100 yds. Both had the barrels free-floated and JP triggers/hammers installed. One was shooting Hornady Custom ammo and the other was shooting my excellent reloads, using Berger match bullets.

 

[cfullgraf]

I thought the chrome bores in the military rifles was to alleviate corrosion problems of the bore in tropical environments.

 

[Shear_stress]

Chrome is only $40 extra on RRA AR barrels.

Might have something to do with barrel makers being able to amortize the cost over umpteen ARs. A lot fewer M1As being made.

As for the OP, I like a chrome lined bore. Easier to clean, less likely to rust and I'm not enough of a rifleman to be able to discern the difference in accuracy versus an unlined bore. Either that, or the rifles I have with chromed barrels aren't really built for precision shooting anyway.

 

[Girodin]

My understanding is that chrome lined barrels are not as accurate.

This is generally true. However there are some chrome lined barrels that are built to exacting standards and very accurate. Noveske comes to mind. Their chrome lined barrels will shoot sub MOA. At the same time they are going to have a much longer service life. They are not going to be as accurate as a Noveske SS barrel but will shoot as well as some other SS barrels. The following is an excerpt from an interview with John Noveske.

Crane: Light Carbine barrels. You’re double chromin’ ‘em, and obviously, you must be getting a pretty nice even chrome job on there.

Noveske: Yes. I have a tolerance that is equal to a match-grade barrel.

Crane: Equal to a stainless barrel?


Noveske: Well, that doesn’t mean anything, because there’s a lot of different makers of stainless barrels, but there is a kind of an unspoken match-grade tolerance in the custom barrel world of 2/10ths of a thousoundth concentricity, or…in uniformity of bore diameter from end to end, and I spec that out on my chrome-lined barrels.

Later in the same interview

Crane: If you’re settin’ up an AR carbine for somebody, most of the time, are you gonna’ recommend the stainless polygonal?

Noveske: Well, it depends. I ask them what they’re gonna’ do with it. The stainless-barreled uppers and rifles that we sell are a precision carbine. The chrome-lined light carbines are…for the guy that says he’s gonna’ beat it up, he’s gonna’ abuse it, he’s gonna’ train hard, he’s gonna’ do full-auto mag dumps, that’s the gun for that kind of treatment. The guy that’s gonna’ be sniper, counter-sniper, or anything precision…

Crane: What if you’re doin’ a lot of…let’s say you’re gonna’ compete in 3-gun with it on semi-auto, and you’re just gonna’ do a lot of rapid fire semi-auto shooting and stuff like that, then what?

Noveske: Either one’s fine. They’re both very accurate. I’ve got groups that people have sent me with both barrels under half an inch at 100 yards, so it’s kind of like I’m competing with myself.

Crane: If you’re looking at both the stainless barrel and the chrome-lined barrel, what’s standard MOA on these guns, on these barrels.

Noveske: Stainless barrels–and I’m not sayin’ this from what I’ve shot. This is reports from customers—The typical end-user report on my stainless barrels is about .6 MOA, and the Light Carbine barrels, most everything I hear is sub-MOA, and that means it can be three quarters of an inch [3/4" MOA] or half an inch [1/2" MOA].

Crane: So stainless is gonna’ be a little bit more accurate, but not much.

Noveske: Right, ’cause they’re both very accurate, already.

Not all chrome lined barrels are the same nor are all SS barrels.

 

[Coal Dragger]

I had a chrome lined barrel that had a bad plating job done to it, and have replaced it with a cold hammer forged 4150 CMV barrel that is nitrocarburized (melonite). So far the nitrocarburized barrel is superior in every way that I can measure at this point. For those less familiar with nitrocarburizing it is a form of salt bath nitriding that chemically alters the steel making it much much harder. Similar hardness to hard chrome but it achieves a greater depth than chrome can plate to. It should make for a very durable and corrosion resistant barrel.

On a side note the cold hammer forged barrel is superbly smooth inside with no machine or tool marks, it picks up virtually no copper fouling.

 

[stubbicatt]

I had a chrome lined barrel that had a bad plating job done to it, and have replaced it with a cold hammer forged 4150 CMV barrel that is nitrocarburized (melonite). So far the nitrocarburized barrel is superior in every way that I can measure at this point. For those less familiar with nitrocarburizing it is a form of salt bath nitriding that chemically alters the steel making it much much harder. Similar hardness to hard chrome but it achieves a greater depth than chrome can plate to. It should make for a very durable and corrosion resistant barrel.

On a side note the cold hammer forged barrel is superbly smooth inside with no machine or tool marks, it picks up virtually no copper fouling.

+1

There are many aspects of my new SIG556 which are impressive to me, but the one that astounds me is how quickly that barrel cleans up, and no visible copper fouling either. This I attribute to the CHF and melonite process.

 

[meanmrmustard]

Ill take Melonite over CL thank you.

 

[hentown]

You're welcome.

 

[briansmithwins]

Hardchrome gives you a few advantages:

Corrosion resistance, as other have mentioned.
Ease of extraction. Hardchrome is slipperier than steel.
Increased barrel life. Hardchrome is more resistant to flame cutting than steel so the throat lasts longer.

The disadvantage is that, because of the way hard chroming is done, hardchromed barrels may be less accurate. Hardchroming also costs more.

Depending on what you're doing with a gun, the advantages may or may not outweigh the disadvantages.

On any AR pattern rifle that may see serious use, I'd insist on a hardchromed chamber and barrel. ARs are known for weak extraction, hardchromed chambers help extraction, and a FTEx is a really, really, bad malfunction when you need a rifle to be working.

BSW

 

[Coal Dragger]

Melonite (aka Nitrocarburizing) results in a lower coefficient of friction than hard chrome, so extraction should be even better from a melonited chamber. The only real advantage hard chrome has is better resistance to flame cutting due to a higher melting point, which will help keep throats healthy a little longer although the steel underneath the hard chrome is still going to get hot if you run abusive levels of heat.

Otherwise for a rifle barrel that won't be used as a light machinegun I would go with the increased interior and exterior corrosion resistance, deeper hardening of the base material, and lower friction coefficient offered by melonite. When you also add in better likely accuracy that seals the deal for me.

 

[MCgunner]

I always thought chrome barrels were for helping prevent corrosion from corrosive primers common in other countries. The erosion resistance thing makes sense since military rifles get fired a LOT in battle. I don't know of a sporting rifle other than my black powder Cabela's Hawken Hunter Carbine with chrome lining. SURELY, THAT is for corrosion resistance. Not like a front stuffer is going to overheat. I really ain't into military rifles, but have a couple of Norinco SKSs with chrome bores.

 

[CharlieDeltaJuliet]

Well look at the HK MR556. A $3k rifle without chrome lining. Manufacturers swear that chrome lining can make a rifle less accurate. I guess I am beginning to buy into it. Guess I will see, I am looking for a MR556....

 

[Onmilo]

For years and years Colt was notorious for assembling guns from second rate parts then nickle plating the guns to hide the flaws.
Because a part Needs to be undersized or in the case of barrels, overbored, to accept the plating, it was a good way to get rid of what would otherwise end up in the scrap pile,,,,
Since barrels intended for chrome plating have to be cut overbore to allow room for the plating material and all plating is more of an art than a science one will realize quite a bit of variation in bore diameters of chrome lined versions.
This is where the "Chrome Lined Barrels are less accurate" statement comes in.
Fact is, quite a few barrel makers have taken plating back to the level of a science and their plated barrels can be just as accurate as an off the shelf unplated barrel.
Because tolerence levels can be maintained at a much higher level still without plating, a true match grade barrel cut from chrome moly or stainless steel will remain more accurate than a looser tolerenced general purpose barrel, plated or not.

 

[meanmrmustard]

You're welcome.

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