Firearms

AR-15 Barrels 101

A single stainless steel, match grade barrel on a white background

One of the biggest differences in cheap versus high-end AR-15s is the quality of the barrels. We are going to cover the pros and cons of Mil-Spec chrome molly steel chrome-lined barrels versus match-grade stainless steel, non chrome-lined barrels and help you make an educated decision on which is right for the intended purpose of your next AR-15.

Two black chrome-lined barrels, stacked on top of each other, on a white background.
Although it is unlikely that most of us will ever “shoot out” a barrel; chrome-lined barrels handle extensive shooting and adverse weather much better.

Most AR barrels fall into one of two categories: either they are made of chrome molly steel with a chrome-lined bore and chamber, or they are made of stainless steel, which typically does not have chrome lining in the bore or chamber.

First, let me say that if the bore (barrel) is chrome-lined, the chamber will be as well and likewise, if the bore is not chrome lined, the chamber will not be either. Chrome molly steel is harder than stainless steel but our main focus is going to be on the chrome lining vs. non-chrome lining aspects because that is what will have more effect on AR-15 shooters.

The Pros and Cons of Chrome Molly Steel Barrels

M16/M4 Mil-Spec barrels are made of chrome molly steel with chrome lined bores (and chambers). So let’s detail the pros of chrome molly steel barrels that have chrome lined bores and chambers first.

The Pros of Chrome-Lined Barrels

The military loves chrome-lined barrels because of:

  1. Corrosion Resistance.
    This is especially important in wet and saltwater environments. When the military issues M16s to our troops in Vietnam, it was initially issued without a chrome lined chamber, or chrome lined barrel, and without a cleaning kit. This, combined with a very corrosive powder and the wet jungle environment of Vietnam, caused countless deaths to our own troops mainly because of failures to extract the spent round in the chamber during combat. The only way to clear a failure to extract is to run a rod down the barrel and knock the spent round back out. According to the article “Defense Under Fire” in Time magazine dated 9 June 1967; “We left with 72 men in our platoon and came back with 19. Believe it or not, you know what killed most of us? Our own rifle. Practically every one of our dead was found with his [M16] torn down next to him where he had been trying to fix it.” —Marine Corps Rifleman, Vietnam. Though eventually remedied, it illustrates the value of chrome-lined barrels and chambers.
  2. Extended Barrel Life.
    This is the biggest reason the military uses chrome-lined barrels. Every round down range creates heat in the barrel from the hot gasses that the powder creates and the friction of the round, both of which result in barrel erosion over time. The higher the velocity of the round, the hotter the barrel gets resulting in even more barrel erosion. The faster the rounds fire in succession, such as on full auto in the military, the hotter the barrel gets and stays hotter, longer, all resulting in drastically more barrel erosion thus substantially shortening the barrel’s life, commonly referred to as “shooting out” the barrel. An AR-15 with a Mil-Spec barrel identical to the Mil-Spec barrel of the M16 will last roughly twice that of the M16 barrel. This is largely due to the fact full auto rates of fire are exponentially detrimental on barrel life. Non chrome-lined barrels wear out even faster with full auto fire, this is the biggest reason the military uses chrome-lined barrels. Most people, however, will not be able to “shoot out” a chrome-lined AR-15 barrel in their lifetime, and if you do, you should consider yourself very fortunate to be able to shoot this much! “Shooting out,” or wearing out the barrel, will become evident when you can visibly see your chrome disappearing in your bore and your groups keep getting bigger and bigger.
  3. Ease of Cleaning.
    This is a definite side benefit of chrome-lined barrels and chambers. Some people think this is only slightly easier to clean, however my experience is that it is substantially easier and faster to clean. So, in short, chrome-lined barrels protect you from erosion and corrosion and easier cleaning is a bonus!

The Cons of Chrome-Lined Barrels

The biggest disadvantage of chrome-lined barrels is long-range accuracy. When a barrel is chrome lined, even with the best technology available today, it is not perfectly even. Because it is not perfectly even on the inside of the barrel, there are very slight high points that obviously will negatively affect the accuracy of the bullet. However, this is only noticeable at long ranges. There are plenty of chrome-lined barrels out there that will give you sub-MOA accuracy, which means a three-round group in less than one-inch at 100 yards.

People will disagree as to the ranges it becomes noticeable, but it is the author’s opinion that it is beyond 300 yards—beyond three football fields. Just to be very clear, the average soldier or civilian with some training should be able to hit a man-sized silhouette target at 300 yards with an AR-15/M16 that has chrome-lined barrel.

Even with a chrome-lined barrel, the biggest factor holding back the shooter’s accuracy beyond 300 yards is going to be shooter error, lack of training, or practice for probably 90 percent of the shooters out there.

The Pros and Cons of Stainless Steel (Match Grade) Barrels

A single stainless steel, match grade barrel on a white background
Match grade barrels offer few advantages at ranges below about 300 yards, but at that distance and especially beyond, the accuracy difference becomes obvious. This makes stainless steel, match grade barrels and absolute must for long-range target shooters.

The second major category for AR barrels are stainless steel barrels, which are typically not chrome lined in the bore or chamber, and these are known as “Match Grade” barrels.

The Pros of Stainless Steel Barrels

Extreme benchrest shooters, NRA High Power Long Range shooters and Civilian Marksmanship Program (CMP) shooters all demand “match grade” barrels—meaning barrels made of stainless steel that are NOT chrome lined. “Match grade” barrels are more accurate and the longer the range, the more apparent this becomes.

The Cons of Stainless Steel Barrels

The cons of match-grade barrels are that they wear out faster, they are harder to clean and they don’t resist corrosion as well as a chrome-lined barrel. Again, let’s clarify that most shooters will not wear out even a match grade barrel in their lifetime. As far as cleaning goes, if the barrel is broken in or “shot in” correctly, the barrel will have a burnishing that minimizes fouling and subsequently makes the barrel much easier to clean; however, still not as easy to clean as a chrome-lined barrel.

Which Barrel is Right for You?

So you’re probably wondering which is right for you, right? An AR-15 rifle is merely a tool, a tool for doing a job. Which job do you want your AR to do?

The Ideal Barrel for defense or Plinking-to-Medium Range Target Shooting

If you are like most people you are you picking out a tool that would be ideal for you to defend your family, your ranch or your home with and maybe do some plinking to medium-range target shooting.

On the other hand,  maybe you want an AR for the commie invasion of the USA or the total collapse of society? Or even, as my younger friends ask me, “What AR do I want for the zombie apocalypse?”

If the answer is yes to any of these questions, then I would choose an AR-15 with a chrome-lined barrel and chamber. These are very common and is the same barrel configuration the military uses. I wouldn’t care if it was cold hammer forged or not, and if so, that would be a bonus.

The good news is ARs with these features are very affordable. There are two I like for under $900 from www.CheaperThanDirt.comArmalite M15A4 and the Bushmaster Optics Ready Carbine (ORC).

The Ideal Barrel for Extremely Long Distance Shooting or CMP Matches

Fluted barrel in dark gray on a lighter gray background
Let’s face it fluted barrels just look cool. More importantly, the fluting reduces weight and dissipates heat at a much quicker rate than straight stock barrels.

I know what you are thinking, “What if I want a gun that can shoot accurately at extreme distances because maybe I am thinking about participating in state or national CMP matches?”

What you want is an AR with a stainless steel non chrome-lined match-grade barrel, cold hammer forged would be a bonus. In this category, www.CheaperThanDirt.com offers an AR I like for under $1300 – the Rock River Arms (RRA) LAR-15 National Match A4. Rock River Arms is a high quality manufacturer and they won the contract to supply the DEA with AR-15s.

Now you have a better understanding of AR barrels and chrome lining and what will work for your needs. Next we will cover .223 chambers versus 5.56mm chambers and more!

Until then, shoot safely and shoot often!

[jerry]

The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (37)

  1. Sure, it’s not needed for backbone, but Fluted CMV barrels dissipate heat faster due to having more surface area these days you see fluting, dimpling, diamonds etc in every kind of barrel imaginable, not just SS

  2. Fluting is not just for looks. Allmost every fluted barrel you will see is stainless. Stainless is softer and more ductle than chrome molly. The flutes help keep it stiff much like the spine on a sword. Chrome molly doesn’t need it because of how hard it is.

    1. QPQ and Melonite also known as Ferritic nitro-carberizing or nitriding for short is not a coating. It is a treatment that actually changes the properties of the metal. The process infuses additional nitrogen and carbon atoms into the surface of the metal making it harder and smoother without changing the dimensional properties of the barrel. It is harder and more corrosion resistant than chrome without any loss of accuracy.

  3. As I remember the story, the M-16 was designed by Stoner with a chrome lined barrel, but the first ones to arrive in Vietnam had a standard steel barrel for some reason.

    The AR has proven to be an excellent weapon after some teething problems at first. As well as very accurate. However, for long range shooting, I would like to say that my favorite weapon was always my Weatherby MK V in 300 Weatherby Mag. But I always find myself forced to admit that it never could top my old Savage chambered in 30.06. For well over a thousand less.

  4. The powder was not corrosive it was sticky,it was ball powder, Winchester 296 is a prefect example very sticky, primers in some military ammo have corrosive primers for longer storage life.The US ammo doesn’t have corrosive primers anymore.

  5. Guys, I hate thread drift, but since this thread seems to be quite active: Are there any publications (magazines) that have to do solely with AR-15s? I tried dialing up AR-15 “magazines” on the internet and got nothing but 10, 20 and 30 ones for sale. I don’t want a book….just a monthly magazine delivered to the house.

  6. I’m surprised no body has mentioned that many “match” barrels are non-chrome lined chrome moly steel. Krieger barrels even recommends not to use their own SS match barrels for light weight contours as it is not strong enough, unlike CM steel barrels…
    PS-to RPK
    “25.Purchase a Colt LE6920 in any configuration and the guess work is out of the equation. It is already tweaked to perfection.

    Comment by RPK — October 26, 2013 @ 8:11 pm ”
    If you show up to any match rifle/dcm competition with one of those it will be quickly apparent you didn’t bring enough gun and you will be soon shopping for an alternate match rifle. There is no “tweaking” at the factory, it’s put together using lowest bid parts that meet minimum specs(probably less then mil-spec, so it goes to civilian market) and sent out to you. An off the shelf LE6920 is nothing like even the most basic generic DCM match rifle and nowhere near the accuracy of a custom AR match rifle.

  7. Interesting conversation. In Vietnam I saw people hit at extreme ranges by 5.56. However it was not a single shot affair. Lots of targets. I posess 6 Ar style rifles. For long range I use a 24″ barrel with a rifle stock and 6-24 power scope. I also have a .458 Socom which I built for carry to protect against bears ifishing n Alaska.. A real brute. But my favorite AR is my MGI Hydra. I have 5.56, 300 BLK and .458 barrels. Great gun to travel with – a gun with three barrels in a case not a whole lot bigger than a briefcase.. I love the versatility of the AR platform. However my favorite long range rifle when I really want to hit what I am shooting at is my handy Remington 700 in 7mm/08.

  8. There are match grade, chrome lined barrels available. My Fulton Armory FAR 308 has one. It was a bit pricey compared to others but it gives the best of both worlds. I notice the article didn’t really even discuss CHF or cold hammer barrels vs standard. A CHF barrel is actually more dense than a standard barrel due to the hammer forging. The chamber and bore are supposed to be perfect every time, compared to a standard barrel that could have a tight chamber if the chamber reamer is dull, etc.

    If you get a chance check out my AR 15 and AR 10 videos on Youtube under eustace2c2 http://www.youtube.com/user/eustace2c2

  9. Jerry,

    thank you for your quality write-up.
    Let me ask a more complex question:
    What are your thoughts on the suitability of 41V45 CHF barrells without (!) chrome lining?

    The Ruger SR556E is one of such rifles (no meloniting eitehr) . Will the quality of that steel offer extra hardness and oxidation resistance?

    I love the SR556E otherwise since it feels so high quality, is tight and I love the chromed piston system. This would be a great SHTF gun but the unchromed barrel for the “E” version runs counter to that.
    Thoughts?

    To confuse matters further the ultra high dollar HK MR556 the “civilized” version of the HK416 also lacks chrome lining. HK has supposedly said that the quality of their barrel steel makes this unneccessary as its hard and corrosion resitant enough to enough the accuracy advantage of unlined.

    thanks for any comments you might render.

    Fred

  10. thanks Neil. When it comes to guns every ones got their own opinions. Look at the 9 vs 45 arguments all over the web. It boils down to what feels good for you and what you shoot well with. The AR platform is a man toy, It can be dressed up and altered any way you want like a barbie doll (my friends cringe when I make that comparison) but with a little practice you can accurately put a lot of well aimed shots down range in a short amount of time.

  11. The AR-15 Lower can be used with .300 Blackout for a larger caliber upgrade because its a 5.56 with the neck area removed to load a 7.62/.308 bullet. Texas allows you to use 5.56 rounds for Deer and Hogs and people have had a lot of success with that round. Although I’ve never hunted a feral hog I’d personally feel more comfortable with a 180 grain .308. Shoots almost flat out to 200 yards (drops like a rock after that) and big enough to take out any hog.

  12. Yes, I understand that it is easy to switch the upper receiver from the .223 to other larger calibers. At this time, however, I am not sure if I need or even want to go in that direction. I have no interest in hunting larger animals such as deer and am interested only in varmints. Wild pigs: another story altogether. If I lived in states where pigs are a problem, I would add a larger caliber upper receiver for pig eradication, but pigs are absent in the varmint country where I shoot.

    Texas has a giant pig problem, but it takes paying for a guided hunt (I talked to several ranchers in the panhandle) or having friends who are ranchers. Apparently, the guide companies have most/all of the land leased, and privateers such as me are not welcome. Sad, considering that the pig problem is reportedly rampant in Texas. Seems than an AR in large-caliber format would be perfect for hunting tuskers.

  13. Neil,
    When I was an LT. I was asked several times why I didnt go sniper to which I had to reply Officers can’t be snipers. I once took out a 400m target, standing unsupported, with someone elses rifle and iron sights. Took two shots.

    Ron,
    I have long wished the army would adopt the Corps Basic Training and most especially the Rifle Marksmanship training. Combat troops should get the bulk of the training but in todays world of asymmetrical warfare everyone should be proficient with their assigned weapon and familiar with others.

    BTW There are a lot of very good AR platforms in 7.62 and the SCAR 17 is a sweetheart. Sub minute of accuracy with standard off the shelf ammo and almost no recoil.

  14. I pick up my first AR-15 in ten days; I sign the transfer papers today. I know nothing about how these rifles shoot, but I found one with a 20″ stainless barrel, LaRue upper, Rock River lower, Nickel-Cobalt bolt carrier group, Magpul furniture. It will be an interesting departure from the bench-rest rifles I am used to. If I don’t manage to shoot any coyotes, I am confident that they will be duly frightened, if nothing else. It will be a good adventure to see what the rifle can do at 300 yards, which since I shoot in brushy country, is usually a range beyond which coyotes have not approached me in the past. The scope sits much higher on the AR than on my Remingtons, so I imagine I’ll have to rethink my trajectory/scope stuff for short and long distances.

  15. DB, Understand about the trade off decisions regarding how much marksmanship training is enough for the force “at large.” The Marine Corps sees it as a foundational skill for all Marines–not just for the infantry or even all combat MOS’s. It helps build a mindset that infuses the concept of who and what we are. We spend (I’d say “invest”) two solid weeks in recruit training on fundamental marksmanship, culminating in “qual day” firing off hand, sitting, kneeling, and prone, all unsupported except by a looped sling, mostly slow fire but including strings of rapid. Known distance of 200, 300 and 500 yards. The targets start small and increase up to man sized at 500. After basic marksmanship, we take them into combat marksmanship for a few days including much closer targets, multi shots, moving and unknown distance. This is supplemented further after recruit training when they all go to the School of Infantry for Marine Combat Training. The same qualification regimen is annual thereafter for all Marines in the operating forces (no longer called the Fleet Marine Force, sigh).

    Many outside the Marine Corps (and even some in it) think THAT much time and ammunition is a mis-allocation of resources. Most of us see it as more than just practical training for those most likely to need it as well as those who will need it unexpectedly. As I said, it’s one facet of the process that helps instill a mindset and self image that pays off in lots of other ways; ways the accountants in green eye shades constantly question. They can’t “count” those intangibles so we constantly have to defend them.

    That said, 500 meters is really only practical with the rifle. As we further embrace the carbine, and rifles become simply unavailable for many MOS’s, this process will “evolve.”

  16. So would I, DB. I guess I’m a sniper at heart. Far too old to try to enter a sniper program, though. I’ve seen what the sniper candidates have to go through, and it takes a tremendous amount of self-sacrifice, both personally and professionally.

  17. Neil,
    Most soldiers can hit jack. Some of it is because of poor training and some is because few people have what it takes to be a good shot.

    Soldiers arent trained for long range shooting and even when they have to its to shoot center mass at a non-moving target. Soldiers are taught to shoot in two positions – prone supported and foxhole supported. They havent taught unsupported shooting since the 60’s.

    Army marksmanship doctrine hasnt changed with the war. We need to train people to shoot long range but army doctrine copied from the soviet battle doctrine dictates fast moving close engagement range combat so thats how they train. Personally speaking I’d rather reach out and touch them before they could get close enough to shoot at me.

  18. DB, I can’t believe that 250 yards is the limit for a .223 round at a man-sized target. I routinely kill ground squirrels (about the size of a beer can) at that range, and with longer (26″) .920-inch diameter SS barrels. Then again, I shoot from a stable bench rest with scoped precision rifles. Perhaps the soldiers shooting with open sights in an off-hand position?

  19. BYoung,
    Suppression has its uses like enabling other elements to maneuver to a position to get a clear shot or find cover. However, in general uncontrolled supression is a waste of ammo. If you can take a clear shot without overly exposing yourself the take it and end the threat. Conserve ammo because it may not be easily available later.

  20. Ron,
    I’ve trained a lot of soldiers and few can hit reliably beyond 250 meters and thats with no one shooting at them. Not always the soldiers fault. The shorten sight picture caused by the shorter barrel of the M-4 is a problem but even more importantly the thrust of military marksmanhip training is suppression and not shoot to kill. Years ago because of the shift to high mobility warfare, expected engagement ranges during combat was supposed to be 100 meters or less. Thats why they went to such a small calibar round.

    Bottom line is the military is just not interested in long range shooting.

  21. “The average soldier or civilian with some training should be able to hit a man-sized silhouette target at 300 yards…” I would hope so. EVERY Marine (NOT just infantry) is trained to hit a man sized silhouette at 500 yards from the unsupported prone, with iron sights. Part of initial and annual requal.

  22. The early rifles in Nam had problems. Rifles produced in the last decade have largely erased those problems due to changes in engineering that have resulted in improvements in parts design and production. Don’t confuse the failures that occurred 50 years ago to the advances that have been made and successes since then.

    Read a very revealing paperback (a large one) from Gun Digest called “The AR-15, Volume 4,” by Patrick Sweeney (found it at Walmart for $18). Mr. Sweeney put modern ARs from several manufacturers through mud, snow, grit, sand, tossed them off rooftops, run over them with a truck, and found few-to-none of the glitches complained about by troops in Viet Nam, proving that the former problems have been largely solved and overcome by modern technology.

    Nice article, Jerry. I also agree that SS barrels are meant for long-distance accuracy and that for most shorter range purposes, including self-defense and plinking, the (usually) longer SS barrels are not needed.

  23. You mentioned the jamming of M16 in Nam, almost any up close pic I’ve seen of SForces in Nam have a cleaning rod taped the side of their M16 to clear that failure to extract, quick!

  24. Once again a well written article. A chromed lined barrel is the best all around option for all but (as you pointed out)serious long range shooters. Even most soldiers (and I’ve trained a lot of them) can’t hit jack past 250 meters and they sometimes get to put a serious amount of rds downrange for practice. Besides in most areas of the north, east, south and extreme west the longest shot you would take is 150 meters or less so a barrel that will give you a MOA at 100 meters is more than good enough. Its easy for trained people to miss at less than 20 feet when under duress so don’t get wrapped around the axle if you can’t make smiley faces at the range like Mel Gibson in the first Lethal Weapon movie.
    The AKM’s (no AK-47’s have been made since 1953) the terrorists use are built to such loose tolerances it doesn’t matter much if the chamber rusts a little because its not chromed. AR’s are built to very close tolerances and a little rust in the chamber could be the difference between life and death. And just as the author of this article stated fully auto fire wears the barrels out quickly and in the case of the AKMs in as little as 200 rds because of the poor quality steel. BTW All AK’s I have seen sold here in the states have chrome lined barrels. I have friends who are Vietnam Vet’s and they told me how they would sometimes shoot out a barrel of an M-16 in a single night. In fairness that was because they kept a 55 gallon drum in their bunker filled with loaded mags and when the Vietcong would attack at night they would just fire full auto and spray around until the rifle got to hot or the drum ran out of mags.

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