Silencer (firearms)
A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a muzzle device that suppresses the blast created when a gun is discharged, thereby reducing the acoustic intensity of the muzzle report and jump, by modulating the speed and pressure of the propellant gas released from the muzzle. Like other muzzle devices, a silencer can be a detachable accessory mounted to the muzzle or an integral part of the barrel.
A typical silencer is a metallic cylinder containing numerous internal sound baffles, with a hollow bore to allow the bullet to exit normally. During firing, the bullet passes through the bore with little hindrance, but most of the expanding gas ejecta behind it is redirected through a longer and convoluted escape path created by the baffles, prolonging the release time. This slows down the gas and dissipates its kinetic energy into a larger surface area, reducing the blast intensity, thus lowering the loudness.
Silencers can also reduce the recoil during shooting, but unlike a muzzle brake or a recoil compensator, which reduce recoil by vectoring the muzzle blast sideways, silencers release almost all the gases towards the front. However, the internal baffles significantly prolong the time of the gas release and thereby decrease the rearward thrust generated, as for the same impulse, force is inversely proportional to time. The weight of the silencer itself and the leverage of its mounting location will also help counter muzzle rise.
Because the internal baffles will slow and cool the released gas and contain gunpowder that is still burning upon exit from the muzzle, silencers also reduce or even eliminate the muzzle flash. This is different from a flash suppressor, which reduces the amount of flash by dispersing burning gases that are already released outside the muzzle, without necessarily reducing sound or recoil. A flash hider, or muzzle shroud, in contrast, conceals visible flashes by screening them from the direct line of sight, rather than reducing the intensity of the flash.
History
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. The muffler for internal combustion engines was developed in parallel with the firearm silencer by Maxim in the early 20th century, using many of the same techniques to provide quieter-running engines, and in many English-speaking countries automobile mufflers are called silencers.
Former president of the United States Theodore Roosevelt was known to purchase and use Maxim silencers.
Silencers were regularly used by agents of the United States Office of Strategic Services, who favored the newly designed High Standard HDM.22 LR pistol during World War II. 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, Donovan, an old and trusted friend of the President, was waved into the Oval Office, where Roosevelt was dictating a letter. When Roosevelt finished, Donovan turned his back and fired a shot into a sandbag he had brought with him, announced what he had done and handed the smoking gun to the astonished president. The British Special Operations Executive Welrod pistol with an integral silencer was also used by the American OSS on clandestine operations in Nazi-occupied Europe.
In 2020, the United States Marine Corps began to field suppressors in its combat units, citing improved communication on a squad and platoon level because of the reduced sound. The USMC purchased 7,000 suppressors in 2020, and planned to have a total of 30,000 by the end of 2023, making them the first armed service to issue suppressors for general usage.
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. As such, "suppressor" and "moderator" have become the suggested terms.The US National Firearms Act of 1934 defined silencers and established regulations limiting their sale and ownership. Both the US Department of Justice and the Bureau of Alcohol, Tobacco, Firearms and Explosives use the term silencer. Hiram Percy Maxim, the original inventor of the device, marketed them as "Maxim Silencers".
The earliest use of the technical term suppressor to refer to firearm noise reduction is in US Patent 4530417, July 23, 1985, "A suppressor for reducing the muzzle blast of firearms or the like". 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.
In 2011, the National Rifle Association of America began a campaign to increase the civilian use of silencers for hunting and sport shooting in the US, setting the goals of easing the restrictions in the Federal NFA of 1934, and in various state laws, regulating the sale and ownership of firearm silencers. In the same year, the American Silencer Association was founded by US manufacturers of silencers, with the same goals of moving silencers into the mainstream. 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 flying supersonically through the air
- Mechanical noise generated by the internal moving parts of the firearm action
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, the louder the muzzle blast, and consequently a more efficient or larger silencer system is required. A gunshot 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.Both types of silencers reduce noise by allowing the rapidly expanding gases from the firing of the cartridge to be decelerated and cooled through a series of hollow chambers. The trapped gas exits the suppressor over a longer period of time and at a greatly reduced speed, producing less noise signature. The chambers are divided by either baffles or wipes. There are typically at least four and up to perhaps fifteen chambers in a suppressor, depending on the intended use and design details. Often, a single, larger expansion chamber is located at the muzzle end of a can-type silencer, which allows the propellant gas to expand considerably and slow down before it encounters the baffles or wipes. This larger chamber may be "reflexed" toward the rear of the barrel to minimize the overall length of the combined firearm and silencer, especially with longer weapons such as rifles.
Silencers vary greatly in size and efficiency. One disposable type developed in the 1980s by the U.S. Navy for 9×19mm pistols was long and in outside diameter, and was designed for six shots with standard ammunition or up to thirty shots with subsonic ammunition. In contrast, one suppressor designed for rifles firing the powerful.50 caliber cartridge is long and in diameter.
Two ancillary advantages of the silencer are recoil reduction and flash suppression. Muzzle flash is reduced both by being contained in the suppressor and by the arresting of unburned powder that would ordinarily burn in the air and intensify the flash. Recoil reduction results from the slowing of propellant gases that contribute 30–50% of recoil velocity. However, some suppressors can increase the backpressure produced by the propellant gases. This can cause them to function somewhat like a muzzle booster and thus increase the felt recoil. The weight of the silencer and the location of that additional weight at the muzzle reduces recoil through the basic mass as well as muzzle flip because of the location of this mass.