AR15: Chrome Lined Barrel Accuracy

[444]

I have read, on this board, many times that chrome lined barrels are not as accurate as non-chome lined barrels. This has been repeated hundreds if not thousands of times since this board came to be. So, several times I have asked for specifics: You would think that if someone makes a statement like that, they would have compared the two and could give me a rough idea of just how much difference there is. But, I have never yet received an answer of any kind to my question of how much difference there is.
I still don't know, but recently (since I moved back into town), I have been doing some shooting from concrete benchrests on known distance ranges at paper targets. I always considered the AR15 to be a very accurate rifle, but was surprised to see some of the groups I was able to produce with a couple of my ARs. I can't compare chrome vs. non-chrome since I don't have any that are non-chrome. All the uppers I have played with so far have been Bushmaster. So far, I have tried three of my ARs on this range: a 14.5" chrome lined Bushmaster M4 type barrel with an ACOG TA31F, a 24" chrome lined Bushmaster V-Match barrel with a 10X Super Sniper scope, and finally an 11.5" (5.5" flash suppressor) Bushmaster upper with A1 type iron sights. With both the M4 and the V-Match I have been able to fire a number of groups of 2" or less at 200 yards using garden variety Remington factory ammo. With the 11.5" barrel I have fired several groups of less than 4" at 200 yards.
With the M4 and the V-Match, we are talking about 1 MOA or less at 200 yards using factory ammo. I also want to say that I am not a good bench shooter. I have done more bench shooting in the last month than I have in my entire life prior to this. I am using homemade sandbags or a bipod.
If I am giving up anything by using a chrome lined barrel I am now even more curious just how much better those non-chrome lined barrels shoot.

 

[stealthmode]

the unevenness of the lining could cause the problem of innaccuracy.maybe its such a small difference that its negligible for plinking but measureable for competition. how are those answers they sound pretty good to me.

 

[Zak Smith]

Also note that the FN SPR and SAKO TRG-42 bolt rifles have chrome lined barrels and generally shoot great.

Will any vendor offer a chrome lined AR15 barrel (or barrelled upper) and basically guarantee 1 MOA? I haven't see anybody, while there are several sources that do so for stainless barrels.

-z

 

[cracked butt]

If you can tell the difference, you should be shooting at Camp Perry.

 

[Zak Smith]

If that were true, then you'd think you would see some chrome-lined barrels at Camp Perry. My impression was that's not the case.

 

[cracked butt]

Like I said, if your skill level is to the point where you are able to shoot standing on your hind legs better than an AR with a chrome lined barrel is capable of, and have the ability to take advantage of the extra accuracy of a premium nonchromed barrel, you should be in the big leagues.

There are people that can do it, and I've seen them do it, but they are the rare exception rather than the rule. There are a lot of sub-moa rifles out there, but very few sub-moa shooters.

 

[Zak Smith]

There are a lot more rifle uses than the 3 or 4 defined positions in High Power, some of which do not require that same kind of skill for sub-minute performance. Trivial examples include F-class, benchrest, and prarie dogging. (They obviously require some of the same and other skills, however.)

ETA:

There are a lot of sub-moa rifles out there, but very few sub-moa shooters.

I freely admit that I cannot shoot sub-minute from H.P. positions, but give me a bipod or ruck and a bean sack, and I usually can. That is exactly what I'm talking about.

-z

 

[Rob96]

I guess the same could be true of the statement, that chrome lined barrels lst longer. Read of an account where the individual had an Olympic Arms AR with an unlined barrel. It went 80,000+ rounds before it started having reliability problems.

 

[Powderman]

Accuracy? Apples and oranges, I suppose. It ddepends on a few variables--how accurate do you want to be; what is the end purpose of the rifle, and how much attention do you pay to the ammunition?

Yes, I said ammunition. It is frequently the overlooked equation.

The .223 (or, 5.56x45 NATO) is a forgiving and accurate cartridge. However, in order to determine just how much more accurate the chrome lined barrel can be than the standard barrel (or vice versa), you would need the following:

1. A pair of rifles (or, two top ends) that are exactly the same, other than the chrome lining;

2. A trigger group that will give a good, light repeatable pull (such as a Jewell unit)

3. Ammunition which has been painstakingly assembled. This means weighing each case, from the same lot number, neck sizing once fired cases, trimming, chamfering, deburring of flash holes, uniforming of primer pockets;

Weighing bullets from the same lot number to ensure that you have enough for a good control group, then three record groups from each rifle;

Finding a powder that will fill the case to the base of the seated bullet, then hand weighing each charge;

Seating each bullet so that it comes to the same place each time--such as, .002-.005 off the lands;

Checking each loaded round for concentricity (bullet run-out);

and, firing from a good machine rest, or a good rest with proper benchrest technique.

Will you notice a difference? Maybe, maybe not. Will it be enough to worry about? Again, maybe and maybe not.

My personal best with five rounds from an AR was right at .300 at 100 yards. This was from a Frankengun--Oly Arms lower, Armalite A4 HB upper, with a chrome lined barrel, and a Simmons Whitetail Expedition 6.5-20x50 scope mounted. The load was the 52 grain MatchKing with 25.0 of Varget.

Did I mention that the barrel was chrome lined?

I fired two groups the same way--thoroughly cleaned the bore, with one patch of Hoppe's, followed by a dry patch, then a scrub with Sweet's, followed by dry patches, then one more of Hoppe's and dry patch until clean.

Completely dried the chamber, cleaned the bolt face and lugs, then fired two rounds of factory for fouling rounds, then the five for group, single loading each round and letting the rifle cool for 5 minutes between shots.

So, how does that stack up? If I have the math right, then at 300 yards--assuming all other things were equal, I should be able to group under 3 inches for that load.

Of course, that might not happen with my rifle. I've never tried it at that distance for accuracy.

Remember that the chrome lining is there to keep you from burning up the leade of the barrel--the all important part right in front of the chamber. With an unlined barrel, it is entirely possible to ruin the leade with 2 to 3 30 round mags in rapid fire--as fast as you can pull the trigger.

 

[GooseGestapo]

The general consensus is that the Chrome barrels will usually yeild approximately 1.5x larger groups than a non lined barrel, given equal quality, and similar construction.

I had a Bushmaster w/chrome and non-chrome uppers.

The Chrome barrel was quite acceptably accurate yeilding frequent 1.25-1.5moa groups. Occasionally a MOA would appear by chance.

But, the non-chrome bbl with same ammo, would yeild .5-1.0moa consistently.

Is the Chrome barrel inferior? NO!

Under conditions of full-auto, or Combat environmental conditions, I would expect it to last 5-10x longer than the non chrome barrel, and the difference in the Non-competition "REAL" world would be non existant.

Different uses for different users.

 

[30 cal slob]

I prefer chrome-moly barrels in full autos, if only to extend life.

Inside 100 yards, I can't really discern a huge difference in groups with chrome vs. stainless. Out to 1,000 yards might be another story.

 

[JohnKSa]

I prefer chrome-moly barrels in full autos, if only to extend life.

It's generally accepted that chrome-lined and stainless steel barrels will outlast chrome-moly* barrels.

*Chrome-moly is short for chrome-molybdenum, a comomon term for a steel alloy that is often used in tools and gun barrels.

 

[Rob96]

For a full auto AR, I would a barrel made of 4150 and chrome lined. For semi auto I think the 4140 barrel is just fine. Just for info 4140 and 4150 are both chrome moly steels.

 

[Steve Smith]

No one has really addressed the question with an answer. 444, the answer is intangible. The reason, as I understand it, is that the chrome lining process is not accurate enough to ensure perfect concentricity along the entire bore. A thick spot here and a thin spot there make a crooked bullet. Since the lining process is variable and inaccurate, we can't just take one example of a lined bore and compare that single sample with a single sample of an unlined bore. The theory behind the "chromed bores are more inaccurate" statement is that if the process is poor and you MAY get a bad lining, then choosing the bare bore is just hedging your bets toward accuracy.

Since no one is going to round up all the ARs (let's hope) in the world and test each to find a statistical difference, we just apply a little pragmatism and common sense.

 

[444]

Steve, you are obviously taking this too far. Obviously no one is going to test EVERY single AR15 ever made and call me with the data. BUT, with as many times as this is repeated on this board, I should get at least some kind of actual personal data.
As an example, GooseGestapo gives his take on the matter and says that in his experience, the non-chrome lined barrel will shoot at least 100% better than a chrome lined barrel. Did he test every AR15 in the world ? No, but appearently he has tested some of them and that small data sample is more than I have ever read since I got on this board.

Maybe I have a motive more than just simple curiosity. I read stuff on these internet gun boards every day and to be honest, I think that most of the time, the guy posting doesn't know what he is talking about. He is just repeating something he read somewhere else. And it gets repeated over and over until it becomes an "Internet Fact". Very often, I see stuff that HAS to be posted in every thread on the subject: it is in the SOPs. It is mandatory. The subject absolutely can't come up without seeing the same replies. I get the mental image of some guy's brain that has a flow chart hard wired into his brain so that if he sees this subject, he makes the chrome lined barrel post just like Pavlov's dog. Even if the reply is somewhat off topic it WILL be mentioned EVERY time. In this case, I bet if you did a search on AR15 barrels, at least once in every thread you find, someone will say that a chrome lined barrel isn't as accurate as a non-chrome lined barrel. If you read every thread ever posted on this board that mentions AR15s, I bet it comes up in 75% of them, even if the topic has nothing to do with barrels. Yet, when you ask for facts/experience/numbers to back this up, you can hear a pin drop. Yet, the next time the subject of AR15 barrels comes up, it WILL be mentioned.
Often I think about someone that is new to guns, or maybe new to the subject being discussed: in this case, AR15s. He wants to buy one, and asks for advice. Someone HAS to mention the barrel thing. So, this guy's imagination runs away with him. He starts thinking that a chrome lined barrel is going to shoot into a seven foot group at 50 feet because not only are they not as accruate at a non-chome lined barrel, they arn't accurate at all. They are junk. Stay away from them. Even if someone offers you one for free, don't take it. Why ? Because the experts on the internet said so.
Of course, in reality, a standard production, run of the mill, nothing special at all , Bushmaster with a chrome lined barrel will shoot sub MOA groups at distance using standard, factory ammo purchased at WalMart. And, it will do it most of the time, if the shooter is up to it. Do I base this statement on the testing of every Bushmaster chrome lined barrel ever made ? No. But I own nine of them personally and am not just talking out of the wrong end.
Does this mean that the statement is a myth: No. At least I don't think so. I think that a small but elite group of shooters can tell the difference. Does that make it something that should be mentioned, with no explanation every single time the subject comes up ? I don't think so, but by the same token I know it will never change.

 

[lycanthrope]

Well here's my $.02 and it's worth maybe double that.......

Having shot a lot of AR's...both chrome lined and not....it's awful hard to tell.

Why? Well, I have never shot a free floated match grade AR that was chrome lined. I really can't isolate all the variables, but if they shot that well, I suppose at least one manufacturer would offer chrome lining in a varmint or CMP model.

On the other hand, I'm no Camp Perry miracle, but I can shoot under .5 MOA with my RRA/White Oak A2 with the irons at 100 yards. It certainly shoots better than the Bushy Carbine with optics.........

I also have a carbine that is not chrome lined and it still holds 1.5 MOA ofter ALOT of rounds. How many people burn out an AR and how many rounds does it take? I'm currently throat eroding a 7STW, but that's along way from the 5.56.

 

[Samuel_Hoggson]

accuracy

Well, I would have thought chromed barrels would shoot as well as non-chromed, but my 6600 is good for maybe 1.25 MOA with good ammo (not M193, obviously). My brothers Match Target (just like my HBAR, but politically correct, and bore not chromed) does better, about .75 MOA.

Sam

 

[Zak Smith]

Barrels in High Power, benchrest, F class, long range/precision, etc, are replaced between 1000 and 8000 rounds (depending on caliber) to ensure a certain level of accuracy. If chrome lined barrels offered the same accuracy as non-lined (and typically SS) barrels with longer life, wouldn't we see them used in these comps?

Before you scoff, serious competitors typically try all sorts of things that most of us would consider way more pathological than simply trying a different barrel material.


-z

 

[444]

Again, I am not in any way/shape/form disputing the fact that one is more accurate than the other. We all realize that if this wern't true, then those people shooting in the most demanding applications would be using them. I think that is an established fact and is beyond dispute.
My question is about degree.
My belief is that the difference is slight and of no concern to the average buyer of an AR15. I might even go out on a limb and guess that most people that buy AR15 type rifles couldn't tell the difference. My point is that this is basically a non-issue unless the person was talking about a serious match rifle. Yet, it is brought up each and every time like it is something you should seriously consider because you might not be able to hit a beer can at 25 yards without the latest, state of the art, top of the line match barrel. What seems even more curious to me is the almost daily occurance of someone posting a thread about how they can obtain the cheapest possible AR15 type rifle, and then someone mentions that a chrome lined barrel isn't as accurate as a non-chrome lined barrel.