Silencer (firearms)

In 1892, Swiss inventor Jakob Stahel patented a silencer intended for killing cattle, though he claimed it could be adapted to other firearms too. In 1894 another silencer for use with firearms was patented by another Swiss inventor, C.A. Aeppli. American inventor Hiram Percy Maxim, son of Maxim gun inventor Hiram Stevens Maxim, and co-founder of the American Radio Relay League, is usually credited with inventing and selling the first commercially successful silencer around 1902. He received his patent on March 30, 1909. Maxim gave his device the popularly trademarked name "Maxim Silencer," and it was regularly advertised in sporting goods magazines. OSS Director William Joseph "Wild Bill" Donovan demonstrated the pistol for President Franklin D. Roosevelt at the White House. According to OSS research chief Stanley Lovell, ==Terminology==

Gun rights advocates, gun media and the firearms industry generally claim that the word "silencer" is defined as meaning total silence, while "suppressor" or "moderator" are defined as meaning only reduced sound intensity, in spite of its original definition. Both the US Department of Justice and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) use the term silencer. In UK English, moderator is the more commonly used term. The Oxford, American Heritage, and other dictionaries apply the term suppressor to such contexts as electromagnetic shielding devices, genetics, and censorship, but not firearms. These dictionaries define both silencer and suppressor as essentially equivalent and interchangeable, neither applying exclusively or primarily to sound, and both being applicable as much to complete and total quiet or to partial reduction of sound. Along with state and federal legislative lobbying efforts, the NRA and ASA began public information campaigns designed to change the perception of silencers from their association with espionage, assassination, crime or military special operation use, to instead show that silencers can have health and safety benefits, primarily protecting the hearing of shooters and people in the vicinity, and to debunk the perceived myth in popular television, film and video game media that silencers are so effective that gunshot sounds can go totally unnoticed, such as by people in the next room of a building. In 2014, the ASA changed its name to American Suppressor Association "in a continuing effort to dispel myths about suppressors". Gun control advocates have said that changing the name from "silencer" to "suppressor" is semantic propaganda similar to the efforts to avoid terms like "assault rifle" or "assault weapon" in favor of friendlier-sounding language like "modern sporting rifle", while gun-rights advocates make essentially the opposite argument, and also that the widespread term silencer reflects technical ignorance and is poorly defined. ==Firearm noise anatomy==

When discharged, a firearm makes sound from three sources: • Muzzle blast – shockwave generated by high-pressure gases escaping and expanding from the muzzle after the projectile exits the barrel and breaks the functional seal restraining the gas inside the bore • Sonic boom – sharp bullwhip-cracking sound associated with high-frequency shockwaves caused by an object (in this case, the bullet) flying supersonically through the air • Mechanical noise generated by the internal moving parts of the firearm action A silencer can affect only the noise generated by the muzzle blast. While using subsonic ammunition can negate the sonic boom, mechanical noise can be reduced but is nearly impossible to eliminate. For these reasons, it is difficult to completely silence any firearm, or achieve a high level of noise suppression in revolvers. Revolvers have a looser gas seal between the barrel and the cylinder that emits noise from escaping gases. Some revolver designs attempt to overcome this, such as the Russian Nagant M1895 and OTs-38, and the US S&W QSPR. Muzzle blast generated by firearm discharge is directly proportional to the amount of propellant to be combusted within the cartridge. Therefore, the greater the case capacity (i.e. a magnum cartridge), the louder the muzzle blast, and consequently a more efficient or larger silencer system is required. A gunshot (the combination of the sonic boom, the vacuum release, and hot gases) will almost always be louder than the sound of the action cycling of an autoloading firearm. Alan C. Paulson, a renowned firearms specialist, claimed to have encountered an integrally suppressed .22 LR gun that had such a quiet report. Properly evaluating the sound generated by a firearm can be done only with a decibel meter in conjunction with a frequency spectrum analyzer during live tests. ==Design and construction==

A silencer is typically a hollow metal tube made from steel, aluminum, or titanium and contains expansion chambers. It is usually cylindrical in shape, and attaches to the muzzle of a pistol, submachine gun, or rifle. Some can-type silencers, named for their resemblance to beverage cans, are detachable, and can be attached to a different firearm. In contrast, integral silencers consist of an expansion chamber or chambers surrounding the barrel. The barrel has openings or ports that bleed off-gases into the chambers. This type of silencer is part of the firearm, and maintenance of the suppressor requires that the firearm be at least partially disassembled. Military rifles such as the M16 or M14 often use quick-detach suppressors that use coarser than normal threads and are installed over an existing muzzle device such as a flash suppressor and can include a secondary locking mechanism to allow the shooter to quickly and safely add or remove a sound suppressor based on individual needs. the Russian OTs-38 Stechkin silent revolver, and the Russian MTs-116M suppressed sniper rifle, a 12.7mm silenced development of the 7.62mm MTs-116M. The large calibre allows the bullet to be fired at subsonic speed, eliminating a major source of noise, while retaining as much accuracy, range, and effectiveness as possible, despite its reduced velocity. All of these weapons use special, very expensive, captive-piston ammunition; QSPR ammunition resembled metal-cased .410-bore shotgun shells. The cartridge case internally works as a piston to trap the gases; the piston pushes the bullet, but the gases are retained in the cartridge case instead of being expelled noisily. In tests of the PSS, the sound pressure level was 124.6dB, similar to a suppressed .22 rimfire pistol. In the United States, improvised silencers are governed by the same laws as manufactured ones; an improvised muzzle device that reduces sound signature, regardless of original intent, is regulated as a silencer. ==Characteristics==

protruding (completely assembled) Functionally, a suppressor is meant to diminish the report of a discharged round, or make its sound unrecognizable. Other sounds emanating from the weapon remain unchanged. Even subsonic bullets make distinct sounds by their passage through the air and striking targets, and supersonic bullets produce a small sonic boom, resulting in a ballistic crack. Semi-automatic and fully automatic firearms also make distinct noises as their actions cycle, ejecting the fired cartridge case and loading a new round. Aside from reductions in volume, suppressors tend to alter the sound to something that is not identifiable as a gunshot. Silencers are particularly useful in enclosed spaces where the sound, flash and pressure effects of a weapon being fired are amplified. Such effects may disorient the shooter, affecting situational awareness, concentration and accuracy, and can permanently damage hearing very quickly. By reducing noise, recoil and muzzle-blast, it also enables the firer to follow through calmly on their first shot and fire a further carefully aimed shot without delay if necessary. Wildlife of all kinds are often confused as to the direction of the source of a well-suppressed shot. In the field, however, the comparatively large size of a centerfire rifle suppressor can cause unwanted noise if it bumps or rubs against vegetation or rocks, so many users cover them with neoprene sleeves. While this is similar to the energy available from the .45 ACP pistol cartridge, the reduced diameter, and streamlined shape of the heavy .30 caliber bullet provides far better external ballistic performance, improving range substantially. The .300 Blackout is another cartridge that was largely developed for use with a silencer, it was also based on the .221 Fireball and the .223 Remington as well, and is essentially a higher pressure .300 Whisper. It was originally developed in 2009 for the U.S. military, who wanted a .30 caliber cartridge that was more powerful and more versatile than the 5.56x45mm when fired from the M4's shorter barrel, as the 5.56mm was designed for the M16's barrel, and would also function in the M16/M4/AR-15 platform and STANAG magazine with only a barrel swap. The other requirement the military requested was a round that would have superior functionality in a suppressor, with subsonic loads that had better terminal performance and quieter sound, as they found 5.56mm subsonic loads were seriously lacking in power. This led to the .300 Blackout, the case design allows it to have a wide range of bullet weights and muzzle velocities, with its supersonic loads commonly using bullets with muzzle velocities of (respectively) and roughly of muzzle energy; conversely common subsonic .300 Blackout loads use bullet weights of with muzzle velocities of (respectively) and a muzzle energy of about . Most .300 Blackout suppressors with subsonic rounds have their sound level reduced to between 135 to 130 dB, with an average decrease of 36 dB (8 times quieter), which has led the .300 Blackout become one of the most popular rounds to use with a suppressor, and one of the most popular semi-automatic sporting rifle rounds period. 9×19mm Parabellum, a very popular caliber for suppressed shooting, can use almost any factory-loaded weight round to achieve subsonic performance. These 147gr weight bullets typically have a velocity of , which is less than the speed of sound. sniper rifle and AS Val assault rifle The Soviet/Russian armor-piercing 9×39mm ammunition used in rifles such as the AS Val has a high subsonic ballistic coefficient, high retained downrange energy, high sectional density, and moderate recoil. Without using subsonic ammunition, the muzzle velocity of a supersonic bullet can be lowered by other means, before it leaves the barrel. Some silencer designs, called integrals, do this by allowing gas to bleed off along the length of the barrel before the projectile exits. The MP5SD is an example of this, with holes right after the chamber of the barrel used to reduce a regular 115 or 124gr ammunition to subsonic velocities. ==Effectiveness==

Live tests by independent reviewers of numerous commercially available suppressors find that even low-power, unsuppressed .22LR handguns produce gunshots over 160 decibels. Another study evaluated two calibers of rifle and nine suppressors, .223 caliber AR-15 (five suppressors) and .300 caliber AAC Blackout (four suppressors), and reported noise reduction of the peak sound level pressure between 7 dB and 32 dB. The De Lisle carbine, a British World War II suppressed rifle used in small numbers by Special Forces, was recorded at 85.5 dB in official firing tests. Measurements relying upon sound level meters are often unable to capture the waveform details to accurately describe the impulse. ==Regulation==

The legal regulation of silencers varies widely around the world. In some nations, such as Finland, France, and New Zealand some or all types of suppressors are essentially unregulated and are sold through retail stores or by mail-order. • Denmark: the Danish Weapons And Explosives Law makes the unlicensed possession of a silencer illegal. it is legal to own and use silencers for hunting. • Finland: a firearm silencer is classified as a firearm part by law. Purchasing a suppressor requires a firearm ownership permit, which must be shown to the vendor at the moment of purchase. • Italy: a silencer is considered a restricted firearms accessory, which can only be sold to the armed forces, police and government agencies.(Law april 18 1975 Art. 2). The exception to this is any silencers acquired before 4 November 2013, where these items can be freely retained and used. No registration is needed for these. • Norway: not regulated and can be purchased by anyone for any firearm. No licence or permit is necessary. • Poland: In 2020, a new amendment to the Arms and Ammunition Act allowed police to issue permits for firearms with sound suppressors for hunting permits. Hunters are allowed to use them only for the sanitary shooting of animals. • Portugal: Silencers "Sound Moderators" are permitted for hunters and sport shooters since 22 September 2019. As they are only classified as accessories, prior authorization is not required for their acquisition, and they can be purchased by gun license holders upon presentation of the respective gun license. Moderators don't need to be registered • Russian Federation: firearm silencers use (legally defined as "devices for noiseless shooting") is prohibited, and dealers are prohibited from selling them, but there is no penalty for purchasing or possession of such devices. • Sweden: Since 1 July 2022, silencers are regulated the same way as ammunition. Anyone who has the right to possess a certain weapon for shooting may possess silencers that fit the weapon. • United Kingdom: Sound Moderators are regulated as controlled components and require an entry on the owner's firearm certificate (FAC). It is generally taken that good reason to possess the firearm "should normally imply "good reason" to possess a sound moderator". In 2024, the U.K. Government undertook a consultation on removing sound moderators from licencing controls entirely. North America • In Canada, any device designed to muffle or stop the sound of a firearm is classed as a "prohibited device" under the Criminal Code, effectively making them illegal for civilians to own, use, transport, or import. The federal legal requirements to manufacture a silencer in the United States are enumerated in Title 26, Chapter 53 of the United States Code. Oceania • In Australia, silencers were made prohibited under the Weapons Prohibition Act 1998, use and ownership of silencers is generally limited to government, security, and law enforcement use only. However, following the Firearms Regulation 2017 some states like New South Wales and Queensland changed the law to allow certain individuals with a firearms license to obtain a Prohibited Weapon Permit from their state police to legally possess and use a silencer. Silencer permits are typically only issued to professional and occupational shooters like state licensed hunters for animal population control, competition shooters that belong to a government licensed gun club, hunters hunting on private land that belong to a government approved hunting club, and farmers that have a depredation license to shoot varmints, pests, and predators threatening their livestock. • In New Zealand, following firearm law changes in April 2019, suppressors could still be fitted to a standard firearm. ==See also==