I have long felt there is a need for a better muzzle brake. There are many effective muzzle brakes designs available. I feel there are elements that are often compromises or oversights found on many options available today. While a common and often overlooked item on many firearms, I believe a muzzle brake is far more critical than most realize. I will explain the methodology behind the Plumb Precision Products Muzzle Brake (P3MB). It is my hope that this often-overlooked feature will garner the attention it deserves.
The act of firing a cartridge in a firearm generates a rapid pressure spike within the chamber, bore, and body of a firearm’s barrel. This causes the barrel to resonate and vibrate in a helical, or twisting fashion. Pressure waves move down the length of a barrel at about 3 times as fast as the projectile. Once the wave reaches the crown of the barrel, they return. This oscillation repeats until the high material density in the barrel finally suppresses the energy expended. Proportions of the barrel directly affect harmonic effects and therefore accuracy.
The harmonic oscillations of the barrel affect 2 initial phases of the projectile’s ballistics. It effects the entirety of the projectile's internal ballistics while in the barrel. It also effects the initial part of its external ballistics.
These effects need to be optimized, to limit their negative effects on accuracy. Accuracy is achieved when harmonics are optimized. This means consistent and repeatable effects on the barrel are key. Ideally, pressure waves align to keep the muzzle diameter, in particular the crown, with a tight dimension when the projectile leaves the barrel.
Affecting the barrel’s crown will alter accuracy. Altering or damaging the crown makes the rifle less consistent. Will the rifle still be accurate enough to continue being effective? Yes, but we are not here to discuss effective. Barrel manufacturers spend enormous amounts of time and money to determine the optimal length, profile, and crown shape. Accuracy is not easy or cheap to come by. The fastest way to make a mess of it is to adversely affect the crown of the barrel. The crown is best left pristine and uninfluenced.
Since the very first part of external ballistics is also affected by the barrel harmonics. Ideally the maximum energy oscillating through the barrel is compressing the bore as the projectile is leaving. Additionally, high-pressure gas, which is traveling just as fast (or faster) as the projectile, will leak to some degree past the projectile. Once the projectile is exiting the bore the gas begins to openly spill outward, the crown takes on more significance.
Crowns are commonly milled at an 11-degree angle. This allows the fast moving and high-pressure gas to expand efficiently outward into the low-pressure atmosphere. If this high-pressure gas is given a path of least resistance that is asymmetrical, it will affect accuracy and controllability in that direction. Much like the controllable vectored exhaust on the F-22, the extra or uneven flow might alter the projectile’s path during the initial stage of flight.
Anything that changes, constricts, or effects the crown negatively effects the flow of high-pressure gas around the projectile and must be avoided at all costs.
Some current muzzle breaks adversely affect the crown of the rifle barrel. All muzzle brakes will have some effect on the rifle barrel. At a minimum the materials and weight will influence barrel harmonics to some degree. Some designs have effectively little influence on the crown of the rifle barrel. Other designs have very adverse effects on the crown and the initial stages of projectile flight.
These negative effects are caused by not allowing immediate gas evacuation away from the projectile and undue interference with the crown of the rifle barrel. Both will be described,
Smokeless powders produce about 1 liter of gas per gram. There are almost 2 grams (30 grains) of powder in each 5.56 cartridge. Considering the rifle’s operating group use of gas, and other losses, it is safe to say that approximately 1.5 liters of gas, at common atmospheric pressures, is expelled from the barrel each time a 5.56 rifle is fired.
Muzzle brakes commonly deal with gasses though chambers, ports, and vanes that direct gas in the manner chosen. My philosophy focuses on chambers, directional ducting, and a concept I call “gas scraping”.
The first chamber needs to allow for the immediate evacuation of initial gas release. When the cartridge is fired, there is at least a small amount of gas the escapes through the barrel grooves and past the projectile. These gasses are a very small amount of the gas produced by when the cartridge is fired. Regardless, these gasses need to be dealt with as we can start to set the conditions for the flow of gas that follows the projectile.
The first chamber must have reward negative space to allow for efficient flow away from the projectile. This element has several positive effects. It clears the initial gasses that have escaped past the projectile. While not an immense concern, it is best to set the conditions from the very beginning.
We allow for these initial gasses, which are traveling in a speed greater than that of the projectile, to be evacuated towards the rear. The motion of gas has a predictable distribution based on volume, pressure, temperature, and speed. This predictable distribution of gas is known as Maxwell-Boltzmann distribution. Furthermore, Kinetic Molecular Theory (KMT) expands on how we can utilize the flow of gas to our advantage. KMT encompasses several noble gas laws.
One in particular is Amontons’s law, that we will take it in its inverse. This means if the gas temperature is decreased, the speed and energy of the gas molecules decreases. If the volume of a chamber is increased, there will be a decreasing temperature and speed of gas molecules. Ultimately, this results in less force being applied. Which means the further from the point of highest pressure the gas flow starts work in our favor, the less effective the brake will be.
So, starting at the highest-pressure point, the crown of the barrel, we manipulate the flow of gas to our advantage. We applied the maximum force to the walls of the first chamber of the brake. For maximum effect, as close to the muzzle as we should. Simply, if we all allow the gasses to expand and cool, they become weaker, so everything starts at the crown.
Our first chamber leaves the crown almost fully exposed and untouched. This allows for the immediate gas evacuation under Maxwell-Boltzmann. We open to a near ambient pressure environment for the projectile, as it leaves the barrel. The design also prevents any undue contact with the muzzle. The very first amounts of gas that escape (in front of the projectile) are instantly manipulated to provide the ideal environment for the projectile and for stability of the firearm.
Each of the following chambers are designed to allow the escaping gasses to expand while being slowed. This allows the projectile to be affected less by the gasses that follow it. It also allows the gasses that do eventually push past the previous chambers to still flow without adversely affecting control of the firearm. There are many non-obvious and proprietary elements surrounding gas flow on P3MB that provide the most stable muzzle break solution. While it looks simple there is a lot going on.
The muzzle brake is also made of materials that do not change barrel harmonics. This allows the barrel to resonate as designed, removing any constructive and destructive harmonic interference. We seek advantages wherever we might find them, no matter how small.
For an example of another small advantage, we provide a 6 o'clock divot so that pin and weld jobs are much easier to start.
It is our intent to provide the most stabilizing muzzle brake without any negative affect on the projectile. We deliver a muzzle break with the most positive effects for the shooter and the rifle. Look for the Plumb Precision Products Muzzle Brake (P3MB) from your favorite retailers.