When I was shopping around for a rifle that I wanted to use for precision shooting, one of the decisions I had to make was between a heavy barrel or a thin barrel. After some research, it became clear that in order for a rifle to deliver a high degree of accuracy, I need the least possible deflection of the barrel as the bullet exits the muzzle. So the question remained, can this deflection be reduced with a heavy barrel that has more rigidity? Are heavy barrels more accurate?
A heavy barrel can be 2 inches more accurate at 100 yards than a thin barrel, according to this test between a heavy barrel and a light barrel under sustained fire conducted by Andrew Morgan. This is because heavy barrels have more rigidity and are less affected by heat warp and harmonic vibrations.
The added weight of a heavy barrel also reduces the recoil of the rifle, which means there is less disturbance to the barrel as the bullet leaves the muzzle. Less recoil also makes it easier for the shooter to fight their reaction to flinch as the shot is released.
Heavy barrels, or bull barrels as some people will call them, have been a favorite among precision rifle shooters for years, and the reasons are obvious. Let’s look into more detail as to why bull barrels, or heavy barrels, are inherently more accurate than the thinner barrels found on most sporting or hunting rifles.
Why are heavy barrels more accurate?
A lot of people will insist that there is no real difference in accuracy between a heavy barrel and a thin barrel. That might be true when you are shooting no further than 200 yards or so, but if you want to shoot more accurately, and at longer ranges, then the differences will start to become obvious when comparing a thin barrel to a heavy barrel. But WHY are heavy barrels more accurate?
Heavy barrels are inherently more accurate because:
- Heavy barrels have better barrel harmonics
- Heavy barrels are less prone to “heat flex” or “heat warp”
- The extra weight of a heavy barrel reduces recoil and disturbance to the rifle
1. Heavy barrels have better barrel harmonics.
When a shot is fired, the entire barrel of the rifle vibrates along the centerline of the bore, much like a guitar string. The thinner the barrel, the higher the amplitude of these vibrations. High amplitude vibrations will have a greater negative effect on the accuracy of the rifle. By adding thickness to your barrel, you essentially decrease the amplitude, making the barrel more accurate.
In simple terms, more rigidity equals less vibration, which means less deflection.
It is worth mentioning that it’s possible to further decrease the amplitude of these vibrations by attaching something heavy to the end of the barrel. This is why a lot of shooters notice an increase in accuracy after attaching a suppressor to their rifles, and that is one of the reasons I make use of a heavy suppressor when shooting long-range.
2. Heavy barrels are less prone to “heat flex” or “heat warp”, increasing the accuracy of the barrel.
“Heat flex” or heat warp, is one of the biggest negative effects on accuracy when it comes to shooting. “As barrels heat up they have a tendency to change the point of impact for your gun, and even a fraction of an inch of movement in the barrel could be enough to throw your shot completely off paper downrange.” says one writer at thetruthaboutguns.com
According to this test in the video below, a lightweight barrel can cause a point of impact shift of more than 2 MOA as the barrel heats up during sustained fire, that’s 2 inches at 100 yards, where a heavier barrel had almost no point of impact shift.
What exactly is heat wrap? Heat warp happens when the barrel heats up during shooting. The metal expands slightly, and if the bore of the barrel is not absolutely concentric to the barrel profile, the uneven expansion of the metal can warp the barrel just enough to cause a point of impact shift.
Heat flex can also change your barrel harmonics which will temporarily affect your zero. When the barrel cools down, the point of impact will return to your rifle’s zero. If you are just a hunter, and only intend on taking one shot at a time, then you will be fine with a lightweight barrel because It won’t heat up enough to cause any warping.
3. Heavy barrels are more accurate because the extra weight reduces recoil.
Heavy barrels have a third effect that will inherently increase the accuracy of the rifle (and the shooter), and that is less recoil and less muzzle jump. How does a heavy barrel reduce recoil?
A heavy barrel has more weight. According to Newton’s Law of Inertia, the inertia of a heavy object is less affected by an equal force on a lighter object. Less movement, or recoil to the rifle, means less disturbance to the rifle while the bullet leaves the muzzle, resulting in more accurate shots.
Reduced recoil of a heavy barrel will also benefit the shooter by making it easier to fight their reaction to flinch as they release a shot. If the shooter can flinch less, there will be less disturbance to the rifle as the bullet exits the barrel, which will translate into a more consistent shooting.
Do heavy barrels last longer?
So it is clear that there are huge benefits to choosing a heavier barrel for long-range and precision shooting. But are there any other benefits to carrying around the extra weight (other than the extra exercise)? What about barrel life? Do heavy barrels last longer?
Heavy barrels last longer because there is more material to absorb heat. A heavy barrel heats up slower than a thin barrel. In a thin barrel that heats up fast, heat will soften the metal, making it more malleable. The more malleable the metal, the more wear there will be inside the barrel, shortening the barrel’s life.
The difference in barrel life between a thin and heavy barrel might be small, but it is a welcomed benefit on top of the fact that it is indeed more accurate. If you are very concerned about barrel life, you should take into account other more important factors that shorten the barrel life. These include the caliber, amount, and type of propellant used, the pressure of the round, and the rate of fire.
Is a heavy barrel the same as a bull barrel?
For the sake of this article, when I am referring to a heavy barrel, I am referring to anything thicker than a normal profile barrel. But let’s clarify the difference between a heavy barrel and a bull barrel. Is a heavy barrel the same as a bull barrel?
No, not necessarily. The terms “heavy barrel” and “bull barrel” are used interchangeably by a lot of shooters, but “bull barrels” are in fact slightly thicker than “heavy barrels”. Most shooters consider a barrel that is 0.75 inches thick or more a heavy barrel and anything 0.92 inches or thicker is considered a “bull barrel”
You can tell if you have a heavy barrel or a bull barrel by looking at the taper of the barrel profile from the chamber end to the muzzle. A heavy barrel (or any other barrel profile) will have a noticeable taper, getting thinner as you reach the muzzle end. A bull barrel will have little to no taper at all and will be noticeably thicker at the muzzle end.
Choosing a barrel profile is highly dependent on the purpose of the rifle. Is the rifle going to be used for hunting? If so, then you will want something that is adequately accurate at shorter distances, and is easy to carry around in difficult terrain as you track an animal, and for this reason, you might be better off with a thinner sporter type barrel.
However, if long-range above-average precision is important to you, then you are going to have to sacrifice some mobility and opt for a heavy barrel. A heavy barrel is going to heat up slower and will be less affected by warping and flexing, as well as yield a slightly longer barrel life. A heavy barrel will also be more rigid and will have better barrel harmonics, that’s less vibration and equal more accuracy. Furthermore, a heavy barrel will reduce the recoil and muzzle jump, making the rifle more comfortable to shoot and makes the shooter less prone to flinching.