Each of these has pros and cons and the balance is between how long it takes, the consistency of the end result, and how much stress the steel undergoes during the process. More length, and more mass, for a given diameter requires a faster twist to stabilize it. Thank you for a very thorough, well-researched, and pragmatic page on AR-15 barrels. We measure how stable a bullet is by applying a gyroscopic stability factor. 223 is a SAAMI specification, so everyone knows how to follow it for the civilian market or reloaders. The two different alloys have different wear characteristics. Just like over cleaning or poor cleaning can damage or wear out a barrel, so can no cleaning at all. The other half of this equation is what happens when the bullet impacts the target. A friend of mine had a .220 Swift barrel that didn’t even make it to 2000 rounds. I’m rebuilding my ar15 pistol, and I’m going to replace the barrel with a good quality, 20” barrel. CM and stainless barrels, machined bare, have about the same level of accuracy. As the charge burns, expanding high-pressure gasses propel the projectile down the bore. So we can leverage this behavior to our advantage. The short version is that the ideal twist rate is a combination of a bullet’s diameter, length, and weight distribution. A manufacturer may claim their barrel is 4150 steel, but that doesn’t mean it’s actually certified under MIL-B-11595E. The vanadium in this alloy helps promote a finer grain structure, wear resistance, and strength. If you don’t care why, just know that barrels shooting slower rounds at lower pressures last much longer than those shooting the barrel burning magnum and varmint cartridges. The same small shop is able to machine, rifle, polish, and lap all in one place. You can read more about that in my article on weight and balance. So let’s start with the best-case scenario for the average shooter. If you are interested in shooting paper for competition, then it’s a moot point. In this article I will discuss what barrel life means to the everyday shooter and how you will know when your barrel is on it’s last legs. One of the original engineers who designed the process founded the company. It’s easier to machine and rated to temperatures down to -40 degrees Fahrenheit. Gas flows down a tube, where it meets the gas key of the bolt carrier group. AR-15 Barrel Life? Shoot less powerful cartridges. The barrel length has a blunt impact on your accuracy. If you shop around enough, you’ll come across retailers selling AR-15 barrels made from “machine gun steel.” FN USA makes these barrels using their blend of steel intended for the M240 and M249 machine guns and it’s a variety of 41V45. Hard for me to believe that people take the magnum rifles to the range and shoot them enough to wear a barrel out. Hey Matt, thanks for commenting! But they’re wrong, and I’m going to tell you why. The 16″ length is the most common AR-15 barrel length sold today. A chrome-moly barrel could have slightly less. But 4 inches of suppressor doesn’t offer the same boost as 4 inches of additional barrel length. Before I get into the technical side of things, I want to remind you of my rules underpinning everything about the choices in front of you: The nice thing is that this over/under is fairly predicable using external ballistics. And here Matt just pulls it all together in an understandable way. Too much gas and the rifle action becomes too violent. Home » Equipment » The AR-15 Barrel Cheat Sheet: Everything You Need to Know. I would write for the site and produce content for free if it was practical, but domains, webspace, and other online services cost money. I own a bushmaster xm15 E2S nato.i believe my 16″ barrel is modified and crooked.im looking for a heavy barrel 20″ to increase my velocity or distance.i disagree about carrying and shooting where you can’t do both,I can.im half blind so the extra yardage of the 20″ compared to 16″ is my preference.so if you know where I can get the hvy 4150 20″ barrel I’m game. It doesn’t do anything particularly better than other options, but it has good all-around performance. On the other hand, a hunter may consider even a 3 minute of angle rifle as accurate enough for the purpose. For a precision shooter this ‘poor’ level of accuracy is simply not acceptable and would be an indication that a barrel change is eminent. A key contributor to barrel life is the size of the powder charge. Working with stainless steel also reduces the wear and tear on tooling. For example, 18″ barrels with rifle-length gas systems have two inches less “dwell time” when compared to their 20″ cousins. The SOCOM program was originally modeled on the Navy SEAL Recce rifle and its 16″ barrel. The primary trade-off is a loss in dwell time between the gas port and the muzzle. But you’re rarely going to find a bare CM barrel on the market. These grooves “grab” the bullet and impart rotation. Gain insights from pros, new content notifications, vendor discount alerts, and more! Good tip A. Upon exit, the bullet begins a ballistic trajectory. Buy from a quality manufacturer and let them worry about how the barrel gets made. In contrast, the average professional competition shooter expends between 20,000 and 30,000 rounds per year. standard M16A2 and A4 barrels and did not meet the accuracy requirement for a light sniper rifle didn’t matter. CHF barrels are, in theory, tougher than barrels made with button or cut rifling, but I sincerely think that it only matters if you’re looking for bragging rights. Thank you for doing it. A barrel’s twist rate describes how quickly the grooves spiral. Dwell time describes the amount of time between when the bullet passes the gas port, allowing gas into the system, and when the bullet exits the bore. We’ll call them Athena Defense. If your barrel loses accuracy at the 1500-round mark, then it only worked for three seconds! This is largely due to the fact full auto rates of fire are exponentially detrimental on barrel life. So let’s start there. I think that should count for something. I often link to products and companies that I receive nothing from because I genuinely think it’s a good product. Use a bore guide when cleaning your rifle. The 18″ rifle-gassed barrel is pretty well figured out at this point. Daniel Watters, who I leaned on heavily for the SCHV series, did an outstanding job assembling the history. Barrels are expensive and should only be replaced when necessary. But as it tends to go, bureaucratic red tape caused more headaches. In the AR platform, the civilian model of the HK is probably the best way to go, but you will of course pay HK prices for it. Unless you have some special purpose in mind, such as competition shooting or making YouTube videos of mag dumps, then this is where you should start. I will build another 18 inch but I am worried about my lack of knowledge regarding the 18 inch barrel and gas systems; whether to use a mid length or rifle length and the proper gas port. Great article. This produces a well-balanced rifle that dissipates heat well. I wasn’t overly subtle in the paragraph above. Remember though that the extra mass also retains heat longer and so not only do you have a heavy barrel to carry around, but you have to wait longer for it to cool down too. AR-15, AR-10, and AR-9 Barrels manufactured by Bear Creek Arsenal. They might even perform quite well, though not as well as Wildcard’s spec. I use 223, 22-250, 220 Swift, and 243 for Varmints and the 22-250 and the Swift have both needed new barrels around 1500 rounds. As the late Hognose of Weapons Man once put it, “You can carry it all day, or you can shoot it all day, but not both.”. The same applies to 4140 steels. The truth is people don’t treat their rifles the same. Those descriptions are very broad, with many sub-varieties falling under those labels. Chrome lined barrels will typically last much longer. You can carry it all day, or you can shoot it all day, but not both. I want to leave you with one more piece of advice. These barrels deliver tight groups and consistent performance all day, so long as you don’t abuse them. (In fact, I think that particular vendor uses the same photos for the fluted barrel upper as they do for the standard barrel upper. So the program office changed the specification to 18″ and said that there wasn’t anything in the system. If I like how it’s going, I may in the future decide on a 6.5 Creedmoor build for… Read more ». In this category, you are no longer concerned with weight. In short, if you ask a precision shooter, barrel life is the expected number of rounds through a barrel before accuracy degrades below one minute of angle at 100 yards. One Security Forces Airman put it to me this way: the 20″ barrel is easier to shoot, but harder to live with. There are three methods that manufacturers use to form the rifling of a barrel: cutting, button rifling, and hammer forging. To be up front, I just don’t have much experience at all with piston systems. This chart shows a plot of starting muzzle velocities of an M855 projectile fired from various barrel lengths. Of course, if you are shooting a “long-lived” .308 Win that goes 5000 rounds before losing accuracy, then you get a whopping TEN seconds of barrel life. When selecting your barrel, you’ll choose between Chrome Moly or Stainless Steel. Let me know if this article was helpful, and feel free to ask any other questions you might have. Don’t spend an excessive amount of money chasing accuracy. It is from GFM Machine, which produces most of the hammer forging machines in the world. Historically, this negatively impacts accuracy. The XM177 “Commando” had a 10.5″ barrel and saw service in Vietnam. Put another way: the more specialized you make your rifle for a specific task, the worse it perform at others. The .220 Swift is a round that puts much more pressure on a barrel then the humble old .308 (one of the reasons why .308 is so great). Do you have any articles on piston operated systems that have info to help me decide which to buy? Great article, and tons of information. On an AR-15, the gas port is on the top of the barrel under the front sight tower. The noise and concussion become unbearable, especially indoors where permanent hearing damage will occur without protection. And that was being generous. You should replace your barrel when the barrel no longer provides the accuracy that you require from the rifle. For rifle barrels, this expansion negatively affects the accuracy of a barrel. Most of us will never shoot that much. Of course, this varies from manufacturer to manufacturer. Longer barrels translate to increased weight and more cumbersome handling. Learn how your comment data is processed. That means a more gentle recoil impulse and longer parts life. The longer the barrel, the more velocity the projectile starts with. When we talk about the effective range of a bullet, we are talking about the maximum distance the bullet can travel and still have the desired effect on a target. I will use this as a reference. I have another barrel from Centurion Arms made of FN’s machine gun steel and double-thick chrome lining that shoots about 1 MOA with good ammunition. Thanks for reading, Jack! Both companies are now selling barrels from the same factory, on the same machines, but one has a much higher spec product. Stainless barrels are popular for match rifles for one primary reason: they are easier to machine and finish. These tend to offer substantially lower recoil and are usually much cheaper to purchase ammunition for. Eliminate the variables! I think those fears are a little overblown, but I understand where they’re coming from. I’m still wondering if it’s worth spending a little extra on a CHF/BFH barrel. You pretty much leave it at “Buy from a quality manufacturer and let them worry about how the barrel gets made.” OK, but I still have to choose the barrel, and that doesn’t tell me if a CHF barrel from a good source will actually last longer or shoot better, or by how much. Generally, that is wrong. If you don’t mind spending a little more, the A5 system is great. There’s little practical difference in accuracy between a light barrel and heavy barrel for the first few shots. I want to use 300 aac because I want to be able to hunt with it as well as target shooting. Thanks for coming by and asking. What barrel length would you recommend? If I can also get a percentage from a retailer selling the product, then great, but it’s not a primary motivator. I don’t mean fantasy land expectations of the big igloo, either. Many of us fall into the trap of buying things for the wrong reason and then try to shoehorn them into roles they’re not suited for. I’ve picked these lessons up from years of reading, competition, training, practice, and writing articles for this blog and elsewhere. In case you are unfamiliar with these cartridges they are all based on the same .308 Winchester case, with the smaller bores obviously being higher pressure and faster shooting rounds. You can always double check to confirm barrel wear, and the need for replacement, with a bore scope. 416r is an alloy formulated by Crucible Industries specifically for gun barrels. Regardless of its origins, the 18″ AR-15 barrel is very popular in the competition world. Notice the temperature used during the stress relief process: 1000 degrees. At this point we would say that it has reached the end of its barrel life. For you, this means that you could land a hit with less holding over the target or adjustment to the sights. Due to a shortened supply chain and skilled craftsmen all working in one place, the finished product is cleaner and more consistent from barrel to barrel. The velocity required to punch a hole in a piece of paper or ring a steel plate is one thing. It’s sorted out now, but 18″ barrels used to have a bad reputation for being undergassed in cold weather because of this. This is pretty well optimized for a 20″ rifle, 16″ midlength, or 14.5″ carbine barrel. That’s a fancy way of saying that the barrel could suffer catastrophic failure under fatigue.