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'[[File:AMX-10RC 017-frein-de-gueule.jpg|thumb|The muzzle brake of the 105mm main gun on an [[AMX 10 RC]] armoured car.]] [[File:4-14 Marines in Fallujah.jpg|thumb|The muzzle brake of an [[M198 howitzer|M198 155mm howitzer]] venting propellant gases sideways as the howitzer is fired.]] [[File:AKM muzzle brake.jpg|thumb|The [[AKM]] rifle's slant-cut muzzle brake]] [[File:Smith-et-Wesson-modele-500-p1030121.jpg|thumb|The [[S&W Model 500]] pistol features a muzzle brake.]] [[File:Muzzle break 30mm mauser machine canon.jpg|thumb|The muzzle brake of a 30mm Mauser [[autocannon]].]] [[File:Air force female sniper.jpg|thumb|The arrowhead-shaped muzzle brake on the [[Barrett M82]] anti-materiel/sniper rifle.]] [[File:PGM-Hecate-seul-img 1008.jpg|thumb|The prominent muzzle brake of the [[PGM Hecate II]].]] A '''muzzle brake''' or '''recoil compensator''' is a device connected to the [[firearm muzzle|muzzle]] of a [[firearm]] or [[cannon]] that redirects propellant gases to counter [[recoil]] and unwanted rising of the barrel during rapid fire.<ref>[http://www.nraila.org/glossary.aspx Muzzle brake] in the NRA Firearms Glossary</ref> The concept was first introduced for artillery and was a common feature on many [[anti-tank gun]]s, especially those mounted on [[tank]]s, in order to reduce the area needed to take up the strokes of recoil and kickback. They have been used in various forms for rifles and pistols to help control recoil and the rising of the barrel that normally occurs after firing. They are used on pistols for [[Practical shooting|practical pistol]] competitions, and are usually called compensators in this context.<ref name=limcat>[http://www.stiguns.com/USPress/gungames/limcat.html STI article] on Limcat Undergas Bypass Turbo System recoil compensator</ref> == Rationale == [[File:MuzzleRise.png|thumb|Illustration of forces in muzzle rise. Projectile and propellant gases act on barrel along barrel center line A. The shooter resists the forces by contact with the gun at grips and stock B. The height difference between barrel centerline and average point of contact is height C. The forces A and B operating over moment arm / height C create torque or moment D, which rotates the firearm's muzzle up as illustrated at E]] The interchangeable terms [[muzzle rise]], muzzle flip, or muzzle climb refer to the tendency of a handheld firearm's front end (the muzzle end of the barrel) to rise after firing. Firearms with less height from the grip line to the barrel centerline tend to experience less muzzle rise.<ref name="Sweeney2012">{{cite book|last=Sweeney|first=Patrick|authorlink=Patrick Sweeney (gunsmith)|title=The Gun Digest Book of the AR-15|url=https://books.google.com/books?id=qTh5yxEVqdoC&pg=PA269|date= 2012|publisher=Gun Digest Books|location=Iola, Wisconsin|isbn=1-4402-2868-X|pages=269–269}}</ref> The muzzle rises primarily because, for most firearms, the centerline of the barrel is above the center of contact between the shooter and the firearm's grip and stock. The [[reactive force]]s from the fired bullet and propellant gases exiting the muzzle act directly down the centerline of the barrel.<ref name="Sweeney2012"/> If that line of force is above the center of the contact points, this creates a [[torque|moment]] or [[torque]] rotational force that makes the firearm rotate and the muzzle end rise upward. The [[M1946 Sieg automatic rifle]] had an unusual muzzle brake that made the rifle climb downward, but enabled the user to fire it with one hand in full automatic.<ref name="Paulsen2008">{{cite book|last=Paulsen|first=Gary|title=The Rifle|date= 2008|publisher=Paw Prints|isbn=978-1-4395-1757-4|page=277}}</ref> == Design and construction == Muzzle brakes are simple in concept, such as the one employed on the [[90 mm M3 gun]] used on the [[M47 Patton tank]]. This consists of a small length of tubing mounted at right angles to the end of the barrel. Brakes most often utilize slots, vents, holes, baffles, and similar devices. The strategy of a muzzle brake is to redirect and control the burst of combustion gases that follows the departure of a projectile. All muzzle brake designs share a basic principle: they partially divert combustion gases at a generally sideways angle, away from the muzzle end of the bore. The [[momentum]] of the diverted gases thus does not add to the recoil. The angle toward which the gases are directed will fundamentally affect how the brake behaves. If gases are directed upward, they will exert a downward force and counteract [[muzzle rise]]. Any device that is attached to the end of the muzzle will also add mass, increasing its inertia and moving its center of mass forward; the former will reduce recoil and the latter will reduce muzzle rise. Construction of a muzzle brake or compensator can be as simple as a diagonal cut at the muzzle end of the barrel to direct some of the escaping gas upward. On the [[AKM]] assault rifle, the brake also angles slightly to the right to counteract the sideways movement of the rifle under recoil. Another simple method is porting, where holes or slots are machined into the barrel near the muzzle to allow the gas to escape.<ref>[http://www.magnaport.com/hgun.html Mag-Na-Port] handgun porting information</ref> More advanced designs use baffles and expansion chambers to slow escaping gases. This is the basic principle behind a linear compensator. Ports are often added to the expansion chambers, producing the long, multi-chambered recoil compensators often seen on [[International Practical Shooting Confederation|IPSC]] raceguns.<ref name=limcat /> == Venting direction == [[File:Custom XD-40 V-10.jpg|thumb|[[Springfield-Armory]] Custom [[XD-40 V-10]], showing the ported barrel and slide]] Most linear compensators redirect the gases forward.<ref>[http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=5594&title=AR-15+LEVANG+LINEAR+COMPENSATOR LeVang linear compensator]</ref><ref>http://www.joeboboutfitters.com/KIES_Blast_Master_Linear_Compensator_p/kies-blst%20mstr22.htm KIES linear compensator</ref><ref>https://www.youtube.com/watch?v=PY4-fmql19w HERA ARMS linear compensator</ref> Since that is where the [[bullet]] is going, they typically work by allowing the gases to expand into the compensator, which surrounds the muzzle but only has holes facing forward; like any device which allows the gases to expand before leaving the firearm, they are effectively a type of [[muzzle shroud]]. They reduce muzzle rise similarly to the mechanism by which a sideways brake does: since all the gas is escaping in the same direction, any muzzle rise would need to alter the velocity of the gas, which costs kinetic energy. When the brake redirects the gases directly backward, instead, the effect is similar to the [[reverse thrust]] system on an aircraft jet engine; any blast energy coming back at the shooter is pushing "against" the recoil, effectively reducing the actual amount of recoil on the shooter. Of course, this also means the gases are directed toward the shooter. When the gases are primarily directed upward, the braking is referred to as ''porting''. Porting typically involves precision-drilled ports or holes in the forward top part of the [[gun barrel|barrel]] and [[pistol slide|slide]] on [[pistol|pistols]]. These holes divert a portion of the gases expelled prior to the departure of the projectile in a direction that reduces the tendency of the firearm to rise.<ref>[https://books.google.com/books?id=7-EDAAAAMBAJ&pg=PA248&dq=popular+mechanics+1932+the+president+of+a+big&hl=en&ei=JIgVTcvHIM2AnQf50_3fDQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCYQ6AEwAA#v=onepage&q&f=true "Jump Is Taken Out Of Guns By Cylinders On Muzzle"] ''Popular Mechanics, August 1932</ref> The concept is an application of [[Newton's laws of motion|Newton's third law]]; the exhaust directed upward causes a reciprocal force downward. This is why firearms are never ported on the bottom of the barrel, as that would exacerbate muzzle rise, rather than mitigate it. Porting has the undesired consequences of shortening the effective barrel length and reducing muzzle velocity; while a muzzle brake is an extension added to the barrel and does not reduce muzzle velocity. Porting has the advantage for faster follow-up shots, especially for [[Burst mode (firearm)|3-round burst]] operation. == Effectiveness == Though there are numerous ways to measure the energy of a recoil [[Impulse (physics)|impulse]], in general a 10% to 50% reduction can be measured. Some muzzle brake manufacturers claim greater recoil reduction percentages. Muzzle brakes need sufficient propellant gas volume and high gas pressure at the muzzle of the firearm to achieve good measured recoil reduction percentages. This means cartridges with a small bore area to case volume ratio (overbore cartridges) combined with a high operating pressure benefit more from recoil reduction with muzzle brakes than smaller standard cartridges. Besides reducing felt recoil, one of the primary advantages of a muzzle brake is the reduction of muzzle rise. This lets a shooter realign a weapon's sights more quickly. This is relevant for fully automatic weapons. Muzzle rise can theoretically be eliminated by an efficient design. Because the rifle moves rearward less, the shooter has little to compensate for. Muzzle brakes benefit rapid-fire, fully automatic fire, and large-bore hunting rifles. They are also common on small-bore [[vermin]] rifles, where reducing the muzzle rise lets the shooter see the bullet impact through a [[telescopic sight]]. A reduction in recoil also reduces the chance of undesired (painful) contacts between the shooter's head and the ocular of a telescopic sight or other aiming components that must be positioned near the shooter's eye (often referred to as "scope eye"). Another advantage of a muzzle brake is a reduction of recoil fatigue during extended practice sessions, enabling the shooter to consecutively fire more rounds accurately. Further, flinch (involuntary pre-trigger-release anxiety behaviour resulting in inaccurate aiming and shooting) caused by excessive recoil may be reduced or eliminated. == Disadvantages == There are advantages and disadvantages to muzzle brakes. Recoil may be perceived by different shooters as pain, movement of the sight line, rearward thrust, or some combination of the three. Recoil energy can be ''sharp'' if the impulse is fast or may be considered ''soft'' if the impulse is slower, even if the same total energy is transferred.<ref>[http://www.jprifles.com/instructions/Website%20Shipping%20Instructions/RE%20Selection%20Guide1.pdf A muzzle brake manufacturer on pros and cons and recoil reduction of muzzle brakes]</ref> The advantages of brakes and compensators are not without downsides, however. The shooter, gun crew, or close bystanders may perceive an increase in sound pressure level as well as an increase in muzzle blast and [[lead exposure]]. This occurs because the sound, flash, pressure waves, and lead loaded smoke plume normally projected away from the shooter are now partially redirected outward to the side or sometimes at partially backward angles toward the shooter or gun crew. Standard eye and ear protection, important for all shooters, may not be adequate to avoid [[Noise-induced hearing loss#Acoustic trauma|hearing damage]] with the muzzle blast partially vectored back toward the gun crew or spotters by arrowhead shaped reactive muzzle brakes found on [[sniper team]] fired [[anti-materiel rifle]]s like the [[Barrett M82]].<ref name="Wieland2009">{{cite book|last=Wieland|first=Terry|title=Dangerous-Game Rifles|url=https://books.google.com/books?id=gn0YAwAAQBAJ&pg=PT550|date=15 October 2009|publisher=Down East Books|isbn=978-0-89272-902-9|page=550}}</ref> Measurements indicate that on a rifle, a muzzle brake adds 5 to 10&nbsp;dB to the normal noise level perceived by the shooter, increasing total noise levels up to 160&nbsp;dB(A) ± 3&nbsp;dB.<ref>[http://www.lima-wiederladetechnik.de/PDF/Finnish-Government-Silencer-Summary.pdf Summary of a Finnish government report (1992) on silencers, muzzle brakes and noise levels]</ref> Painful discomfort occurs at approximately 120 to 125&nbsp;dB(A),<ref>{{de icon}} and {{en icon}} [http://www.lima-wiederladetechnik.de/Schalldaempfer/Schalldaempfer.htm Schalldämpfer = Gehörschützer für Jäger, data collected on noise levels]</ref> with some references claiming 133&nbsp;dB(A) for the threshold of pain.<ref name="Hearing Protection Basics">[http://www.earplugstore.com/morabshootea.html# Hearing Protection Basics]</ref> Active [[ear muffs]] are available with electronic noise cancellation that can reduce direct path ear canal noise by approximately 17–33&nbsp;dB, depending on the low, medium, or high frequency at which attenuation is measured.<ref>[http://www.peltor.se/Admin/files/20051211214726.pdf Peltor Active Muffs data sheet]</ref> Passive ear plugs vary in their measured attenuation, ranging from 20&nbsp;dB to 30&nbsp;dB, depending on whether they are properly used,<ref>[http://annhyg.oxfordjournals.org/cgi/reprint/46/6/527.pdf Finnish Research paper]</ref> and if low pass mechanical filters are also being used. Using both ear muffs (whether passive or active) and ear plugs simultaneously results in maximum protection, but the efficacy of such combined protection relative to preventing permanent ear damage is inconclusive, with evidence indicating that a combined noise reduction ratio (NRR) of only 36&nbsp;dB (C-weighted) is the maximum possible using ear muffs and ear plugs simultaneously, equating to only a 36 - 7 = 29&nbsp;dB(A) protection.<ref name="Hearing Protection Basics"/> Some high-end, passive, custom-molded earplugs also have a mechanical filter inserted into the center of the earmolded plug, with a small opening facing to the outside; this design permits being able to hear range commands at a gun range, while still having full rating impulse noise protection. Such custom molded earplugs with low pass filter and mechanical valve typically have a +85&nbsp;dB(A) mechanical clamp, in addition to having a lowpass filter response, thereby providing typically 30-31&nbsp;dB attenuation to loud impulse noises, with only a 21&nbsp;dB reduction under low noise conditions across the human voice audible frequency range (300–4000&nbsp;Hz) (thereby providing low attenuation between shots being fired), to permit hearing range commands. Similar functions are also available in standardized ear plugs that are not custom molded.<ref name="Sonic Valve II">[http://www.earplugstore.com/health-enterprises-acu-life-shooters-impact-ear-plugs.html Sonic Valve II]</ref> But, relative to a noise level of 160&nbsp;dB(A), this means that even using ear muffs and ear plugs simultaneously cannot protect a shooter against permanent ear damage when using a muzzle brake, through leaving a shooter exposed to noise levels of approximately 131&nbsp;dB(A) that is 11&nbsp;dB above the point where permanent ear damage occurs. Brakes and compensators also add length, diameter, and mass to the muzzle end of a firearm, where it most influences its handling and may interfere with accuracy as muzzle rise will occur when the brake is removed and shooting without the brake can throw off the strike of the round.<ref name="Wieland2009"/> Another problem can occur when [[sabot]]ed ammunition is used as the sabot tends to break up inside the brake. The problem is particularly pronounced when [[Kinetic energy penetrator|armour-piercing fin-stabilized discarding-sabot (APFSDS)]], a type of long-rod penetrator (LRP) are used.<ref name="Tilstra2011">{{cite book|last=Tilstra|first=Russell C.|title=Small Arms for Urban Combat: A Review of Modern Handguns, Submachine Guns, Personal Defense Weapons, Carbines, Assault Rifles, Sniper Rifles, Anti-Materiel Rifles, Machine Guns, Combat Shotguns, Grenade Launchers and Other Weapons Systems|url=https://books.google.com/books?id=sjmNAgAAQBAJ&pg=PA118|year=2011|publisher=McFarland|isbn=978-0-7864-8875-9|page=118}}</ref> Since these APFSDS rounds are the most common armour-piercing ammunition currently, virtually no modern [[Tank gun#Smoothbore|main battle tank gun]]s have muzzle brakes. A serious tactical disadvantage of muzzle brakes on both small arms and artillery is that, depending on their designs, they may cause escaping gases to throw up dust and debris clouds that impair visibility and reveal one's position, not to mention posing a hazard to individuals without eye protection.<ref name="CarlucciJacobson2007">{{cite book|last1=Carlucci|first1=Donald E.|last2=Jacobson|first2=Sidney S.|title=Ballistics: Theory and Design of Guns and Ammunition|url=https://books.google.com/books?id=pX9Tzs7VuSoC&pg=PA158|date=11 December 2007|publisher=CRC Press|isbn=978-1-4200-6619-7|page=158}}</ref> Troops often wet the ground in front of antitank guns in defensive emplacements to prevent this, and snipers are specially trained in techniques for suppressing or concealing the magnified effects of lateral muzzle blast when firing rifles with such brakes.<ref name="PressNavy1992">{{cite book|last1=Press|first1=Paladin|last2=Navy|first2=U S|title=Seal Sniper Training Program|year=1992|publisher=Paladin Press|isbn=978-0-87364-683-3|page=66}}</ref> Linear compensators and [[suppressor]]s do not have the disadvantages of a redirected muzzle blast; they actually reduce the blast by venting high pressure gas forward at reduced velocity. The redirection of larger amounts escaping high pressure gas can cause discomfort caused by blast-induced [[paranasal sinuses|sinus cavity]] concussion. Such discomfort can especially become a problem for [[anti-materiel rifle]] shooters due to the bigger than normal cartridges with accompanying large case capacities and propellant volumes these rifles use and can be a reason for promoting accelerated shooter fatigue and flinching. Furthermore, the redirected blast may direct pressure waves toward the eye, potentially leading to [[retinal detachment]] when repeated shooting is performed with anti-materiel and large caliber weapons.<ref name="Boatman2004">{{cite book|last=Boatman|first=Robert H.|title=Living with the Big .50: The Shooter's Guide to the World's Most Powerful Rifle|year=2004|publisher=Paladin Press|isbn=978-1-58160-440-5|page=86}}</ref> == US legislation and regulation == The State of California outlaws [[flash suppressor]]s on semiautomatic rifles with detachable magazines, but allows muzzle brakes to be used instead.<ref>{{cite web|publisher =California Department of Justice|title=Department of Justice Regulations for Assault Weapons and Large Capacity Magazines|url= http://oag.ca.gov/sites/all/files/agweb/pdfs/firearms/regs/propregs.pdf|quote=“flash suppressor” means any device that reduces or conceals the visible light or flash created when a firearm is fired. This definition includes flash hiders, but does not include compensators and muzzle brakes (devices attached to or integral with the muzzle barrel to utilize propelling gasses for counter-recoil).|date=1999}}</ref> In February of 2007 Democratic Representative Carolyn McCarthy of New York introduced legislation banning muzzle brakes from civilian ownership. <ref>[https://en.wikipedia.org/wiki/Federal_Assault_Weapons_Ban#Efforts_to_renew_the_ban]</ref>. When questioned about what a 'muzzle brake' actually is on Tucker Carlson's news program she was only able to incorrectly describe it as 'the thing that goes up' on a weapon <ref>[https://www.youtube.com/watch?v=ospNRk2uM3U]</ref> The [[Bureau of Alcohol, Tobacco, Firearms, and Explosives]] (BATFE) made a regulatory determination in 2013 that the muzzle device of the [[SIG Sauer MPX]] Carbine, adapted from the baffle core of the integrally suppressed version's [[suppressor]] and claimed by SIG to be a muzzle brake, constituted a silencer and rendered the MPX-C a Title II [[National Firearms Act|NFA weapon]]. [[SIG Sauer]], the rifle's maker, sued the ATF in 2014 to have the designation overturned.<ref>{{cite news | url=http://www.seacoastonline.com/article/20140410/News/404100392 | title=SIG Sauer sues ATF for calling its 'muzzle brake' a gun silencer | work=Seacoastonline.com | date=10 April 2014 | accessdate=29 December 2014 | author=Dinan, Elizabeth}}</ref> In September 2015, Federal Judge Paul Barbadora upheld the BATFE's ruling.<ref>[http://www.guns.com/2015/09/25/judge-rules-in-sigs-case-against-atf-its-a-silencer/ ''Judge favors ATF in Sig lawsuit: It’s a silencer''], Guns.com, 25th September 2015</ref> == See also == * [[Muzzle booster]] * [[Muzzle shroud]] == References == {{reflist|30em}} == External links == {{Commons category|Muzzle brakes}} * [http://kuulapaa.com/home/highspeed.html High speed photography on muzzle brakes] * [http://www.chuckhawks.com/muzzle_brakes.htm Chuck Hawks'] article on muzzle brakes * [http://www.lima-wiederladetechnik.de/Englisch/Muzzle-Brake.htm Pictures of various muzzle brake types] * [http://www.rvbprecision.com/articles/10/adventures-with-muzzle-brakes Adventures with muzzle brakes] * [http://www.glock.com/english/pistols_c-models.htm Glock's page on Compensated Pistols] [[Category:Firearm components]] [[Category:Artillery components]]'