AR-15s are machines, not all that unlike a car, washing machine, or electric drill. Like any machine, they’re made up of parts that are subject to wear. Use them enough, and eventually, they will wear out.
Not all the parts on an AR-15 are wear parts. Your buffer tube, for example, will probably last a lifetime; it doesn’t experience any significant wear from normal operation, so unless it becomes damaged through misuse or accident, there’s usually no reason to replace it.
Your barrel, on the other hand, will inevitably wear out eventually. Some wear faster, others slower, but all will eventually degrade until impractical or unsafe to continue using.
So when should you replace your AR-15 barrel? When it wears out, of course. There are guidelines for how long that should take, but at the end of the day, no one can predict exactly how long your barrel will last. That length of time is determined by a variety of interconnected factors, including caliber, barrel material, rate of fire, and more.
Despite this complexity, it’s not difficult to figure out when your barrel is starting to go. Below, we’ll take a look at the factors that influence barrel life, signs that your barrel is ready for replacement, and the average round count you can expect from an AR-15 barrel.
AR-15 Barrel Life Factors
AR-15 barrels are slowly degraded simply by using them. Containing an explosion and using it to shove a piece of hot metal through a steel tube is a violent process that inflicts a great deal of stress and heat on the barrel. Over time, this wears away at the throat of the chamber and the surface of the rifling, eventually degrading accuracy and in some cases, reliability.
How quickly this process occurs is determined by several factors.
Caliber
Chief among these factors is caliber. There is no single other bigger influence over the life of your barrel than the caliber in which it is chambered.
Different calibers place an incredibly varied amount of stress on the barrel, owing primarily to surface area, twist rate, and velocity. A training AR-15 chambered in .22 Long Rifle, for example, can easily fire tens of thousands of rounds before accuracy degrades to the point of impacting the function of the firearm. A .22 Nosler, on the other hand, might tap out as early as 2,000 rounds, depending on the other factors at play.
For the most part, common AR-15 calibers tend to be fairly gentle on barrels. 5.56 NATO, .223 Remington, and .300 Blackout barrels will all average tens of thousands of rounds before needing to be replaced.
Barrel Material
Barrel material also has a part to play, primarily in how well it resists erosion. Typically, the part of the barrel that erodes first and results in a lack of accuracy is the throat. This small section at the front of the chamber bears the brunt of the heat from the explosion, which slowly degrades the metal.
Heat, then, is the primary enemy of barrel life. Friction and material erosion have their parts to play as well, but typically heat is the first cause of failure. As such, materials that resist degradation from the blast of the explosion well will last longer than those that don’t.
Chrome tends to be the king of longevity, which is why chrome-lining is one of the most popular barrel treatments in the AR-15 industry. Nitride barrel treatments are not far behind though, which is a large part of their growing popularity. AR-15 manufacturers are constantly experimenting and innovating, though, so you can expect the best barrel coatings and materials to evolve as AR-15 technology advances.
Stainless steel, on the other hand, tends to have a shorter lifespan, which is why it is most commonly found on precision and target rifles where accuracy is prized over longevity.
Barrel Profile
Barrel profile contributes to longevity for the same reason that barrel material does; it affects the way the barrel handles heat. Thicker, heavier profiles tend to absorb and disperse heat more efficiently than thinner barrels, and as such, last longer.
This effect is particularly noticeable when the bulk of the girth is located near the chamber; the farther from the chamber the extra metal is located, the less it will affect barrel life. For this reason, a government profile barrel will typically outlast a pencil barrel by a decent margin, but the longevity gains on a bull barrel as compared to a government profile are marginal at best.
There are ways to mitigate this effect, though, which brings us to our next factor.
Rate of Fire
Every time you fire a shot, a measure of heat is inflicted on the barrel of your AR-15. The instant the powder finishes burning, though, the barrel begins to cool. If you then fire again immediately, another measure of heat is added before the last one has fully dispersed, which can stack up into a higher total temperature and a longer time before the barrel returns to ambient temperature.
This cumulative effect of heat absorption is how rate of fire affects barrel life. The faster your fire, the hotter your barrel gets, and the faster that heat eats away at it.
This interplays with barrel profile and material as well. Because of the greater total amount of metal to act as a heat sink, rapid fire has a less destructive effect on heavier barrel profiles. Lighter ones, though, suffer proportionally more. As such, a government barrel could actually wear out before a pencil profile, if subject to a severe enough firing schedule.
This is also why round count is an unreliable predictor for barrel life. A few thousand rounds could easily be enough to degrade a barrel if fired in a single continuous stream of automatic fire. Spread those same few thousand rounds over a series of range trips and a more moderate rate of fire, though, and the barrel may easily handle twice as much before losing significant accuracy.
Ammunition
Ammunition type, too, plays a role. While much ago is made about case material, powder charge generally plays a more significant role. A hotter loaded cartridge is going to place more stress on the barrel than a lighter one, by simple virtue of the hotter, more powerful explosion.
5,000 rounds of average, off-the-shelf .223 Remington might not burn out your barrel, but if you’re consistently shooting MK262 replica loads or maxing out the powder charge in your reloading manual, expect a commensurately reduced barrel life.
Corrosive ammunition is an even more extreme example of this. Modern, domestically produced ammunition does not contain corrosive compounds, but certain types of surplus or foreign ammunition can, particularly in cartridges such as 7.62x39mm and 5.45x39mm.
Firing corrosive ammo leaves deposits of chemicals in your barrel that are highly dangerous to the metal. Left unaddressed, they will slowly wear tiny holes in the inside of your barrel–which is obviously very bad for longevity and accuracy. For this reason, if you shoot corrosive ammo, it is extremely important that you thoroughly clean your AR-15 barrel after every use.
Average AR-15 Barrel Life Round Counts
As we’ve covered, AR-15 barrel life is incredibly variable. What you’re shooting and how you’re shooting it will go a long way to determining your barrel life. On average, though, an AR-15 chambered in .223 Remington and 5.56 NATO can expect to fire 10,000 to 20,000 rounds before needing a barrel replacement.
But, the best way to determine when your barrel needs to be replaced is not by counting your bullets fired, but by paying attention to how your rifle behaves and knowing the signs of a failing barrel.
Signs Of A Worn-Out Rifle Barrel
As your barrel wears, it will begin to show signs of decreased performance. There are physical indicators too, which can be analyzed by examining the barrel with the right tools, but most users have neither the equipment nor the experience to monitor their barrel this way. Instead, the more practical approach is to pay attention to how your rifle performs.
The first indicator of a failing barrel is typically accuracy loss. You’ll start to see your groups open up, irrespective of other factors. In a precision rifle, this is pretty easy to pick up; the difference between a 1.5 MOA group and a 2 MOA is easily measured when you’re firing from a rest and tracking your group sizes.
In a rifle used for CQB training, 3-Gun competition, or general plinking, though, this can be harder to see. A half-MOA difference in group size won’t be very noticeable if you’re firing quickly from an unsupported position at short range. Even when the accuracy loss becomes more pronounced, it can be hard to know if your barrel is going if you just had too much coffee before heading to the range.
Luckily, there is a surefire way to know that something is wrong and your rifle needs some maintenance: keyholing.
Keyholing is a term for when your bullets impact the target at an improper angle. This can be sideways or diagonally, but the name comes from when they impact vertically, leaving a hole that looks like a teardrop or keyhole rather than a perfect circle.
This phenomenon occurs when your barrel fails to stabilize the bullet before it leaves the muzzle, resulting in it tumbling through the air rather than being held straight by its spiral rotation. While not always caused by barrel wear, keyholing is a sure sign that something is wrong with your rifle.
When viewed in concert with a general idea of round count, keyholing and accuracy loss are clear indicators of barrel degradation, suggesting that your barrel is due for a replacement.
Notable AR-15 Barrel Manufacturers
There are nearly as many manufacturers of AR-15 barrels as there are of AR-15s themselves, so there’s no shortage of options to choose from when it comes time for a replacement. Below we’ll take a look at some of the biggest names.
Daniel Defense
Daniel Defense is a company with no shortage of accolades, but their barrels may nevertheless be one of the best things they manufacture. Widely renowned for both their durability and accuracy, Daniel Defense barrels are among the best on the market.
Their primary claim to fame is their cold-hammer-forged construction. This manufacturing process, aided by Daniel Defense’s experience and expertise, yields a barrel that is extremely accurate and very resilient—both primary factors in some of these barrels’ use by U.S. Special Forces.
Ballistic Advantage
A partner company to Aero Precision, Ballistic Advantage built its reputation on value; you’ll seldom find a better bang for your buck in the industry. Their barrels are well-constructed, pleasingly accurate, and priced such that you’ll still be able to afford ammunition when you’re done.
Ballistic Advantage AR-15 barrels offer a huge variety of lengths, profiles, and calibers, so no matter what you’re building next, they’ve got you covered.
Faxon
One of the best-known names in AR-15 barrels, Faxon has now branched out to handgun parts, rimfire components, and even their own line of complete firearms, most notably the ARAK-21. Throughout all of that, Faxon AR-15 barrels still remain highly competitive in the industry.
Faxon’s greatest claim to fame is their ever-popular Gunner profile barrel, a hybrid design that combines the best of both Gov’t and Pencil profiles to create a barrel that is light, rigid, and accurate, all at once.
Conclusion
AR-15 barrels can last a long time. For many users, they can go for years, or even decades. Those with frequent training regimens or demanding firing schedules, though, might need to replace their barrels yearly, or even more frequently.
Regardless of which camp you fall into, by keeping in mind a general idea of your round count and watching for the signs, you can be sure to catch your barrel when it starts to fail and replace it with something brand new and ready for another few thousand rounds.
