Muzzle Brakes - How Do They Work?

Muzzle Brakes - Just Noise Makers?

Often times we find ourselves engrossed in conversation about rifles, carefully analyzing specifications and other minutiae over a campfire, at a lunchtime break at work, or just about anywhere someone will hear our opinions or thoughts on the subject.  If we talk about rifles for long enough, and particularly about magnum rifles, the subject of muzzle brakes is certain to come up sooner or later. Perusing the internet, asking your buddies, and even consulting gun shop counter 'pros' can produce erroneous concepts and information.  You might be asking "How do muzzle brakes actually work?" or "What percentage of recoil reduction can I expect from this brake?" or even "What make a muzzle brake loud?”  Let’s see if we can shed some light on basic muzzle brake theory and see if we can answer a few of those questions. Since we’ve all graduated Recoil 101, we will now move on to Recoil 102 to learn how the muzzle brake reduces this recoil. KA-1830 An efficient muzzle brake will have an arrangement of ports and baffles to stop the expanding gasses in their forward movement and divert them at a perpendicular (or rearward) direction away from the direction that the bullet is traveling.  Although this is, again, a simplified version of what is going on, let’s recall the last equation that we used during Recoil 101:   ma(rifle)=ma(bullet)+ma(propellant)+.25m(1.25)a {propellant second}   Now assuming our muzzle brake can completely stop 75% of the propellant, then it will counter act approximately 75% of the primary force incurred accelerating the propellant.  This means our new equation will look like this:   ma(rifle)=ma(bullet)+ma(propellant)+.25m(1.25)a {propellantsecond}-.75ma(propellant).   If the ports of the muzzle brake can divert that same 75% laterally away from the bore, then the equation will now be something like below.  Again, don’t let this equation scare you.  What we’ve tacked on is the muzzle brake stopping 75% of the initial propellant gasses acceleration and we’ve also diverted 3/4 of the original 75%  of the secondary propellant gasses recoil, so we are left with only 25% of the secondary (.1875 or 18.75%).   ma(rifle)=ma(bullet)+ma(propellant)+.25m(1.25)a {propellantsecond}-.75ma(propellant)-.1875m(1.25)a {propellant second}   Using the same rifle, bullet, and powder charge, we get the following:   49,000a=15000+5000+1562.5-3750-1171.9, so 49,000a=16640.6, and solving for a, we now get 3.39%   Now you cannot compare this number with the 'bullet only' figure we came up with earlier as you cannot negate the secondary recoil from your scenario.  You must compare it with the real world total for the same rifle, and we see that the 75% efficiency muzzle brake offers a recoil force reduction of 29.7%.  By redirecting the propellant gasses, the hypothetical muzzle brake offered an almost 30% reduction in recoil.  Now I'm sure we've all seen the outrageous claims of recoil reduction from muzzle brakes. "Buy this brake and reduce recoil from your super ultra-uber magnum by 60, 70, or even 80%!"  While impressive numbers can be achieved through how much propulsion gas can be redirected out of the brake, a general rule of thumb is that if you see such claims, you can rest assured they are false.  Whether people selling these brakes don't understand the physics or are using their efficiency numbers to inaccurately inflate their recoil reduction percentage, it’s still wrong. Now we can all see that a more precisely made muzzle brake will let less gas out of the end of the muzzle and redirect as much away from the rifle as possible.  Likewise, a muzzle brake with less efficiency will garner you a smaller amount of recoil reduction as more (or in some cases, most) of the propellant gasses would continue moving forward. One disadvantage that the muzzle brake has stacked up against it is that it only has a few ten thousandths of a second to do its job, so efficiency is paramount.  Therefore, an efficient muzzle brake should have as much baffle surface area and venting cross-section to achieve good efficiency. View of the KA-1830 Cut in Half In this first KA-1830 cross-section illustration, you can see the propellant paths as the bullet is passing through the brake.  As the bullet passes through the brake, the gasses following will hit baffles and vent outward.  Like we said before, the more gas you can slow down and vent will determine how much recoil reduction is provided.  When the propellant stops against the baffles, the pressure is going to force it to accelerate away from the bore of the barrel.  This causes the brake to accelerate in the opposite direction from the path of the propellant.  This is why it is so important that these forces counteract each other.  This is done by arranging the ports of the brake so that they are equal in size, position, and on exact opposite sides of the brake. On most King Armory brakes, they run a '6/45' porting pattern where there are 6 rows of ports separated by 45 degrees and each row is 180 degrees opposed to another row.   This ensures each propellant stream pushes directly against one another, creating a neutral braking effect.  "But what about muzzle brakes that only have porting on the top, like on a pistol?" you might ask?  These aren't muzzle brakes, but are compensators which are mainly used to redirect propellant upward to help hold the muzzle down under recoil. This '6/45' pattern allows for a large amount of venting and baffle surface while keeping muzzle blast out of the line of sight through the top and keeps from stirring up dust/dirt from gasses escaping out of the bottom. KA-0450 A second design that is effective for recoil reduction is an angle-ported arrangement which redirects the propellant gasses rearward, rather than just to the side.  This actually generates a forward force on the rifle or a 'reverse recoil' effect, pushing the brake and barrel forward.  These types of brakes work best on larger rifles such as a 50BMG or .338 Lapua Magnum as they have A LOT of propellant gas. Angle-port brakes have a few disadvantages that make them less optimal for some applications though. Due to the physical requirements of creating the required baffles and ports, they are usually larger and heavier than standard brakes.  Also, because the blast is being directed rearward, in increases the noise level at the shooters position substantially. Another key element in King Armory's angle-port designs is that they engineered in a proprietary gas-trap design which operate as a check valve of sorts to redirect the gasses away from the bore and ensures they keep exiting the brake rearward, rather than bleeding back into the bore.  By trapping the gas, re-directing it, and preventing it from deflecting back where it came from, it creates a 'slingshot' effect of the propellant gasses, ensuring they leave the brake faster, increasing recoil reduction. Example of a KA-0450 Brake Cut in Half Now we've covered what recoil is and how muzzle brakes fight to control that recoil, let’s discuss the benefits to the user.  When firing a rifle with substantial recoil, many shooters will be subconsciously anticipating the recoil.  This causes that involuntary flinch that you may experience all too often.  Many claim that their muzzle brakes actually improved their rifles accuracy, but in all reality, the reduction in recoil actually may have helped alleviate the stress of the recoil on their body and enable them to focus more on sight picture and trigger control. Recoil can keep you from shooting to your potential and can also keep you from practicing as much as you really should be practicing.  How many times have we heard the stories of guys leaving the gun shop with the nice lightweight hunting rifle with a magnum chamber cut into the barrel, head to the range to sight in off a bench, only to leave their rifle in the safe for a year because it kicks too hard?  With a good muzzle brake, that rifle could potentially be much more enjoyable to shoot and lets the new owner spend much more time at the range with it, comfortably. Thanks for spending some time learning about recoil, muzzle brakes, and how they can benefit you.  Before we leave, a big thanks goes out to Joe Venters at King Armory for helping me with the articles content and supplying me with the diagrams as well.  Visit them at www.kingarmory.com to see their complete line of muzzle brakes and other accessories.