Silencer (firearms)
A suppressor, also commonly known as a silencer, is a device attached to a firearm to reduce the amount of noise and flash generated by firing the weapon. It is a cylindrically-shaped metallic tube that is fitted into the barrel. Most suppressors work by allowing the pressurized gases in the barrel to slowly expand before they exit the muzzle of the firearm, resulting in a "phum" sound rather than a bang. The process is comparable to slowly opening a soda can and hearing a "ffft" sound rather than a "pop". Some suppressors are also structured like motorcycle mufflers in order for the sound waves to cancel themselves out as they reflect off of the sides of the casing. Such suppressors are inherently more difficult to produce since they require more precise cutting and assembly. For this reason, they are often bigger and are mounted on large-caliber rifles where the added sound suppression is needed most.
When mounted on pistols and submachine guns, the effective noise reduction of a military grade suppressor is astounding. On the Heckler & Koch MP5 and Mark 23, the weapon's noise is reduced to the point that the click of the action is louder than the muzzle burst. On sniper rifles, and large caliber assault rifles, the noise reduction is still immense, but a distinctive whistle is still present. Another important factor in sound signature suppression is the muzzle velocity of the ammunition. The MP5 and Mark 23 chamber 9 mm Luger and .45 ACP rounds, respectively, both of which are available with subsonic muzzle velocities. In large caliber assault rifles and precision rifles, the bullet itself produces a noticeable crackling sound as it travels through the surrounding air. For this reason, it is more difficult to effectively lower the sound signature of these firearms.
One solution is to lower the muzzle velocity of the cartridge. Some suppressor designs do this by allowing gas to bleed out of the barrel before the bullet exits, others do it with rubber "wipes" that use friction to slow the bullet. While this is effective, it dramatically reduces the range and stopping power of the cartridge. In addition, the wipes in velocity reducing suppressors that use them tend to adversely affect the accuracy, since they come in direct contact with the bullet after it leaves the barrel, and the wipes generally wear out and lose effectiveness after only a few shots.
Oftentimes, a subsonic cartridge may even be more powerful than a suppressed high-power weapon because the bullet mass may be increased to make up for the energy lost by lowering the velocity. A good example of this is the .300 Whisper cartridge, which is formed from a shortened, necked up 5.56 x 45mm cartridge. The subsonic .300 Whisper fires up to a 240 grain (16 g), .30 caliber bullet at about 950 feet per second (290 m/s), generating about 480 ft·lbf (650 J) of energy. By comparison, the standard SS109 62 grain (4 g) bullet at 950 feet per second (290 m/s) would generate only 125 ft·lbf (170 J) of energy, only as much as a .22 Long Rifle cartridge. Since the .300 Whisper is based on the 5.56 x 45 mm cartridge, firearms such as the M-16 rifle can be changed to .300 Whisper by simply changing the barrel.
Most suppressors can be removed by unscrewing them off the barrel, but others, such as suppressors that bleed off powder gasses to reduce the ammunition velocity, are built into the barrel and can only be removed by removing the barrel. Integral suppressors are also more robust than detatchable suppressors, because they attach to the barrel over much of the barrel's length, making them less susceptible to bending if subjected to torque, such as when the firearm is dropped. A detachable suppressor that is even slightly misaligned can come into contact with the bullet, which will significantly degrade the accuracy at best, and at worst can result in the suppressor being ripped off the firearm by the impact.
History
Early suppressors were created around the beginning of the 20th century by a number of inventors. American inventor Hiram Percy Maxim is credited with inventing and selling the first commercially successful models circa 1902. The suppressor was first introduced into the United States Army Air Forces before World War II. Office of Strategic Services agents during World War II favored the newly-designed .22 caliber pistol. The addition of a sound suppressor baffle to the barrel absorbed 90% of the noise. William Donovan, Director of the OSS, demonstrated the pistol for President Roosevelt while visiting the White House. Donovan fired ten shots into a sandbag without interrupting the President as he dictated a letter.
Legal status
Legal regulation of suppressors varies widely around the world. In some nations, such as Finland, some or all types of suppressor are practically unregulated and may be bought "over the counter" in retail stores or by mail order, though in many such countries the firearms themselves are strictly controlled. Other nations, such as Canada, practically forbid their private citizens from owning suppressors, while yet others, such as the USA, tax and regulate their manufacture and sale.
In the United States, it is legal for an individual to possess and use a suppressor, however they must go through the National Firearms Act process administered by the BATFE. Such transfers also require a federal tax payment of two hundred dollars and a thorough background check. Some states go further, and explicitly ban any civilian possession of suppressors.
Despite common misconception that suppressors violate the laws of war, special forces have made use of suppressed firearms in warfare worldwide since their invention. One of the more famous, and most effective, suppressed firearms was the British De Lisle carbine developed in World War II. During the late 1950s the People's Liberation Army procured millions of domestically produced clones of the PPSh-41 submachine gun with integrated silencer for infantry use.
Suppressor design and construction
The suppressor is typically a hollow cylindrical piece of machined metal that attaches to the muzzle of the pistol or rifle. Some others are designed as an integral part of the weapon, and may include an expansion chamber that partially surrounds the barrel (These are often called "telescoping" designs, a reference to old-fashioned collapsing telescopes). The outer casing of the supressor is typically referred to as the can.
The suppressor reduces noise by allowing the rapidly expanding gasses from the detonation of the round to be briefly diverted or trapped inside a series of hollow chambers. The trapped gas can cool and expand, reducing the pressure and velocity as it exits the supressor. The divisions between these chambers are called baffles or wipes (see below). There are typically at least 4 and up to perhaps 15 chambers in a supressor, depending on intended use and design details.
Often, a single, larger expansion chamber is right at the barrel's muzzle, which allows the propellant gas to expand considerably and slow down before most of it begins to encounter the shaped baffles or wipes section of the supressor.
Suppressors vary greatly in size and efficiency. A type developed in the 1980s by the US Navy for 9 mm pistols is 150 x 45 mm (5.9 x 1.77 in) and is good for six shots with standard ammunition or up to thirty with low-powered, subsonic ammunition. The British Sterling suppressor is 350 mm (13.78 in) long and 75 mm (2.95 in) in diameter and will work effectively for hundreds of shots with standard ammunition.
Baffles
Baffles are inner walls which separate chambers and are designed not to touch the bullet as it passes the baffle, typically by having a circular hole at least 0.05 inch / 1 mm larger than the bullet caliber. Baffles are typically metal, either machined solid shapes or stamped sheet metal. A few supressors for small calibers (such as .22 LR) have successfully used plastic baffles.
Baffles are separated by spacers, which keep them aligned and the intended distance apart inside the supressor can. Some baffles are manufactured in one piece with their spacer as part of the baffle.
Modern baffles are usually carefully shaped to effectively divert the gun propellant gases into the chambers. This shaping can be a slanted flat surface, canted at an angle to the bore, or a conical or otherwise curved surface. One popular technique is to have alternating slanted surfaces, angled to one side, then the other, back to the first side, and so on through the stack of baffles.
Some supressors use a single, helical baffle which winds around the bullet hole in a single piece throughout the baffle length.
Baffle lifetime
Baffles usually last for a significant number of firings. They are heated and slightly eroded by the gun's propellant gas rushing past them, and over time that will damage the supressor. Damage happens slowly with steel baffles and slow single shot firing, rapidly with steel baffles and fully automatic firing, and extremely rapidly with aluminum baffles and rapid fire. Some very modern steel baffle supressors can be fired for extended periods of time on fully automatic without damage, and other modern supressors use high temperature alloys such as inconel or titanium for long life and reliable service with automatic fire.
Wipes
Wipes are inner dividers which are intended to touch the bullet as it passes. Wipes are typically rubber or plastic or foam. They may have a hole drilled in them before use, or a pattern cut through at the point the bullet will strike them, or they may simply use the bullet's energy to punch a hole.
Wipes typically last for a small number of firings, perhaps no more than 5 before their performance is significantly degraded.
Liners
Various materials may be used to line the chambers and dissipate or cool the gases; these include metal mesh and steel wool. These are more effective than empty chambers, but less effective than wet designs (see below). Steel wool degrades very rapidly (ten shots or so); metal mesh may last for hundreds or thousands of shots of semi-automatic fire, or somewhat less for fully automatic fire.
Supressors and Silencers
No supressor can completely eliminate the sound of firing a firearm. Even subsonic bullets make distinct audible sounds simply flying through the air and hitting targets, and supersonic bullets produce a sonic boom shockwave as well with a much louder crack. Semi-automatic firearms also make a distinct noise as their action cycles, ejecting the old empty cartridge and loading a new one.
Some supressors do an extremely effective job of quieting the muzzle blast sound from firing, to the point that the action and bullet sounds are as loud or louder than the muzzle blast escaping the supressor. These are sometimes inaccurately referred to as silencers: they do not completely quiet the shot's other sounds.
Very effective supressors either take large total supressor volume, moderately large volume plus many baffles, or wipes. It is possible to design a very small and compact supressor with wipes which effectively silences a pistol; these supressors have a lifetime of as few as 4-5 shots and typically no more than a few magazines of ammunition. Larger wipeless (baffle only) pistol or rifle supressors may be nearly as effective for long lifetimes (hundreds or thousands of shots) but are relatively bulky, clumsy, and heavy.
Most supressors used trade off reduced total volume and weight for somewhat louder noise, which is still significantly tactically useful. The optimum point depends on the supressor's intended use.
Wet supressors
Some supressors, called "wet" suppressors or "wet cans", use a small quantity of water, oil, or grease in the first chamber to cool the powder gasses and reduce the volume (See ideal gas law). The coolant lasts only a few shots before it must be replenished, but while it lasts it can greatly increase the effectiveness of the suppressor. One manufacturer claims a 30% improvement in sound suppression for "4 magazines" (32 to 68 rounds) with the addition of 5 ml of water or light oil to their suppressor. Water is most effective, due it its high heat of vaporization, but it can leak or evaporate out of the suppressor. Grease, while messier and less effective than water, can be left in the suppressor indefinitely without losing effectiveness. Oil is the least effective (and least preferable, as well), as it leaks like water and is as messy as grease, leaving behind a fine mist of condensed oil after each shot.
Advanced types
Some advanced designs use baffles to shift the frequency of the remaining sound beyond the range of human hearing, further reducing noise. These design concepts have been used successfully but are still relatively rare in modern supressor construction.
Improvised
Suppressors can be improvised with any baffling material (Pillow, potato, plastic bottle, etc); These are only marginally useful, and often dangerous to the user. In areas where suppressors are regulated, improvised suppressors are very likely to also be illegal, whether they actually reduce the sound of the firearm or not. Nonfunctioning/dummy silencers are available for replica enthusiasts, and are generally legal in the United States.
Ammunition for use with suppressors
Suppressors are most effective when the bullet's velocity does not exceed the speed of sound. A bullet that breaks the sound barrier creates loud flight noise, or a "sonic boom". For any further increase in velocity higher than the speed of sound, flight noise does not increase significantly. Supersonic flight noise may be reduced somewhat by using a projectile of smaller caliber. Bullets that travel near the speed of sound are considered transonic, which means that the airflow over the surface of the bullet, which at points travels faster than the bullet itself, can break the speed of sound. Pointed bullets which gradually displace air can get closer to the speed of sound than round nosed bullets before becoming transonic.
Firearms for use with suppressors
The type of gun also affects suppressor efficiency. Guns with the least 'leakage' are best, so a sealed breech (e.g. bolt action) is preferable and can be suppressed to the point that the "click" as the striker or hammer falls is the loudest sound of firing. Most autoloading firearms still produce a significant amount of noise from the gun cycling (A video is available here) and the leak of high velocity gas from the breech. Revolvers, due to their 'loose' structure, cannot be made quiet, with few exceptions: The Nagant M1895 revolver used an unusual gas-sealed cylinder that made it suitable for use with a suppressor.
While it seems that any semiautomatic pistol could be fitted with a suppressor, it's not as easy as just threading the barrel and screwing one on. Most semiautomatic pistols in larger calibers, 9 x 19 mm Luger and larger, use a short recoil action. This means that the slide and barrel both recoil backwards for a short distance before the slide unlocks from the barrel, allowing the round to be ejected. This is done to keep the breech sealed until the chamber pressure drops to safe levels. Adding the mass of a suppressor to the mass of the recoiling parts means that it will significantly alter the operation of the gun; in most cases, it stops the slide from unlocking at all, and effectively turns the semiautomatic pistol into a bolt action. This is not always a bad thing, however, as the sound of the action cycling is often louder than the suppressed shot. In addition to this, nearly all short recoil designs are based on the John Browning designed tilting barrel lockup, as used in the M1911. This system uses a tilting barrel, which means that in addition to adding mass, the suppressor also adds rotational inertia, greatly resisting the force that tilts the barrel. Because of the high pressures and close tolerances required, the suppressor cannot be allowed to bend at the joint, or the bullet would hit the baffles rather than passing through the middle. Special mechanisms, called "recoil enhancers" or "Nielsen devices", are used to decouple the mass of the suppressor from the barrel. These consist of a sliding baffle in the rear of the suppressor that is forced back under the pressure of the powder gas, thus forcing the barrel backwards and unlocking the short recoil mechanism. Adding one of these mechanisms increases the complexity and cost of the suppressor, but perhaps also efficiency.
Because of the difficulties of suppressing short action designs, suppressors are easiest to add to smaller caliber pistols. .380 ACP and .22 Long Rifle are both usually blowback designs with fixed barrels, and are easy to suppress. The most commonly suppressed firearms are .22 Long Rifle semiautomatic pistols and rifles; suppressing the firearms allows them to be fired without use of hearing protection. Subsonic rounds are readily available in .22 Long Rifle, and even with supersonic rounds the crack of firing is not uncomfortable. The small powder charges of the .22 Long Rifle keeps suppressors small; many, like those available for the Ruger 10/22, are no larger than a heavy barrel.
Specially designed firearms with integral suppressors provide the best overall result, as the suppressor can be fully telescoped to reduce the overall length of the gun, and the caliber can be chosen for maximum performance with the suppressor. .45 ACP is an ideal choice, since the standard 230 grain (15 g) loading is both powerful and subsonic. Special cartridges are also available designed for use with suppressors. The .300 Whisper is probably the most common of these. It is made by cutting a 5.56 x 45 mm NATO cartridge down to a shorter length, then increasing the neck to accommodate a .30 caliber (7.62 mm) bullet. It is loaded with a heavy bullet, over 200 grains (13 g), at subsonic velocities. This gives it the muzzle energy of the .45 ACP with a far better ballistic coefficient (see external ballistics) for better long range performance. The use of the 5.56 mm NATO as a base case means that it can be chambered in M16 derived rifles with a simple barrel change. In addition to special applications in suppressed firearms, the .300 Whisper has become popular with metallic silhouette shooters due to its low recoil, good long range performance, and very high accuracy.
While suppressors are most accurate with subsonic cartridges, they can be used effectively with supersonic cartridges. The crack of the supersonic bullet cannot be avoided, but the suppressor will reduce the sound of the muzzle blast, and make it more difficult to locate the source of the shot by sound. Suppressors are most effective to the side and rear of the shooter, so a suppressor could be used by a sniper effectively. Observers not in the target area would hear the least, and the crack of the arriving bullet will tend to obscure the location from the area of the target.
Suppressors in fiction
Due to their associations with organized crime and intelligence operatives, suppressors are commonly encountered in fiction. In addition to traditional suppressors, such as the ones used by John Clark in Tom Clancy's Without Remorse, or by many characters in James Bond books and movies, mention is often made of improvised suppressors. In Chuck Palahniuk's Fight Club, Tyler Durden describes a dubious method to silence a gun by drilling holes in it. Various fictions, like the recent fillm Lady Killers, mention the use of a regular pillow for noise suppression, a technique also used by the character Dina Araz in the TV-series 24. In Lawrence Block's short story collection Hit Man, the main character wraps insulation material around a pistol's barrel as a makeshift suppressor. According to the novel Hannibal a soda bottle taped to the muzzle of the gun will reduce the sound of the report. While all these methods may muffle the sound of the shot they are at best ineffective and at worst very dangerous. The BATFE, however, considers any attempt to manufacture a silencer, no matter how effective it may be, to be illegal without proper authorization.
Suppressors in video games
- Sam Fisher of Splinter Cell fame uses a suppressor on his Five-seveN and SC-20K.
- Suppressors are available for many guns in the Metal Gear Solid series, such as the SOCOM and Mk22.
- The Eidos Hitman series makes use of suppressors for silent kills.
- In Resident Evil 4's "The Mercenaries" minigame, one of the playable characters, Albert Wesker, uses a suppressor for his 9 mm handgun.
- In the popular first-person shooter Counter-Strike, a removable suppressor is available for the M4 Carbine assault rifle and Heckler & Koch USP. In both cases, it slightly improves accuracy but slightly reduces the power of the shot. The Steyr TMP also comes silenced but the silencer cannot be removed.
- In Battlefield 2, the sniper and special force class carries a silenced pistol. US troops carry a suppressed Beretta M9, MEC troops carry a supressed Izhmash MR-444, and Chinese troops carry a suppressed QSZ-92.
- In Tom Clancy's Ghost Recon. a silenced Beretta M9 is available as a secondary weapon for several character classes. A silenced Heckler & Koch MP5 is also available. In the expansions, other silenced weapons (including sniper and assault rifles) are available.
- In Tom Clancy's Rainbow Six and Tom Clancy's Rainbow Six: Rogue Spear, several silenced weapons are available. In Tom Clancy's Rainbow Six 3: Raven Shield, a suppressor can be attached to almost every gun.
- In Medal of Honor: Allied Assault, one of the weapons is an early silenced pistol (closely resembling a High Standard .22 pistol) which requires the user to rack the slide after each shot.
- In SWAT 3, SWAT 4, Far Cry, a silenced MP5 (MP5SD series, short for schalldampfer) is available.
- Silencers as common weapon attachments for pistols and SMGs can be found in Jagged Alliance 2.
- The popular First Person Shooter, BLACK, enables users to put a silencer on particular weapons throughout gameplay to enhance the espionage tactics.
- Another popular First Person Shooter, Americas Army, has a possibility to put a silencer on a M4 Carbine.
- In Rareware's GoldenEye 007 the player has the option to use a suppressor on many guns. While in their next FPS Perfect Dark a suppressor featured as one of the add-ons for the main pistol.
- In Electronic Arts' From Russia With Love some guns have compulsory suppressors.
- In Eidos's game Deus Ex, the player may find and add silencers to various weapons. One such weapon is called a stealth pistol. It was designed with an integrated suppressor.
See also
External links
- Howstuffworks article
- Bowers, US suppressor manufacturer
- Advanced Armament Company
- Ase Utra, Finnish suppressor manufacturing
- Gemtech Military & Civilian U.S. Suppressor manufacturer
- Husssh Innovative suppressor design from New Zealand
- Image of a suppressor for the Heckler & Koch submachine guns
References
- Paulson, Silencer History and Performance, Vol 1: Sporting And Tactical Silencers, ISBN 0873649095
- Kokalis, Parker, and Paulson,Silencer History and Performance, Vol 2: Cqb, Assault Rifle, and Sniper Technology, ISBN 1581603231
- Parker, Firearm Supressor Patents: Vol. 1 United States Patents, ISBN 1581604602