(Are they for you?)
(Are they for you?)
First off, let us dismiss a few misunderstandings. The term silencer is not the proper terminology, because no firearm can be totally silenced. But the sound signature can indeed be suppressed,...which is why the actual term for these devices is sound SUPPRESSOR, or just suppressor, for short.
Suppressors are actually legal, although currently heavy regulated. Just like machineguns, grenades, flamethrowers and all sorts of neat stuff, it is in fact LEGAL to own them, as long as you live in a state that is not run by libtards and you obey and follow the ridiculous federal regulations and jump through their hoops. Currently, suppressor ownership is legal in 42 states. They are AL, AK, AZ, AR, CO, CT, FL, GA, ID, IN, IA, KS, KY, LA, ME, MD, MI, MN, MS, MO, MT, NE, NV, NH, NM, NC, ND, OH, OK, OR, PA, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, WY. And using suppressors for hunting is legal in 34 of those, which are Alabama Arizona Arkansas Colorado Florida Georgia Idaho Indiana Iowa Kansas Kentucky Louisiana Maryland Mississippi Missouri Montana (varmints only, not game) Nebraska Nevada New Mexico North Carolina North Dakota Oklahoma Oregon Pennsylvania South Carolina South Dakota Tennessee Texas Utah Virginia Washington West Virginia Wisconsin Wyoming.
That was not always the case. To understand the current state of access to sound suppression, lets dig into the history a bit of how these devices came to be.
The History of Gun Mufflers and How They Work – While the American-born Sir Hiram Maxim (who invented the machinegun) invented the suppressor in 1902 and patented it in 1909, it was obviously inspired by the engine muffler, invented only a few years before, in 1897 in Indiana. (As a side note: In most non-English speaking nations, mufflers are called "silencers", which likely had an impact on why Maxim marketed his device as the Maxim Silencer.) Maxim realized that the boom generated by a gunshot was generated by the speed at which the expanding gasses entered the atmosphere. If that speed could be slowed, the sound could be reduced. In fact, that is how all suppressors work even today. Experimenters have tried all sorts of modified internal mechanisms for suppressors to try to reduce sound the most, with varying degrees of success. But the most common scheme used today is still that which Maxim devised in 1902, which involves use of flow-retarding baffles.
Baffles are, in their simplest form, chamber separators resembling common washers such as you'll find in a hardware store. Using spacers to keep them from collapsing onto each other in the "stack" inside of a tube, the bullet flies through the holes of the baffles, while propellant gas attempts to do so as well. However, as the gas enters each chamber through the bore hole, it expands into and fills that chamber,...then has to fight its own volume to squeeze down to fit through the next baffle into the new chamber, filling it,...then reducing in size once more and repeating the process until the gas finally escapes out the front. While all of this happens in milliseconds imperceptible to your naked ear, it yet reduces the speed at which the gas escapes into the atmosphere, reducing the "sound pressure wave".
Note that suppressors do nothing to attenuate the super-sonic "crack" a bullet makes if/when it is speeding faster than the speed of sound. (Speed of sound varies depending upon altitude and humidity, but generally is referred to for ammunition purposes as 1000 feet-per-second, more or less.) Rifle cartridges are nearly always super-sonic, while only some handgun cartridges are sub-sonic. Thus, suppressors are most efficient in total sound suppression with handguns or other weapons chambered in handgun calibers. Although even high powered rifles can be be made greatly more comfortable to shoot by reducing muzzle blast.
As you might imagine, when Maxim's device hit the market, many people were excited by the idea, especially in over-populated Europe, where so many people lived so close together without much open spaces as compared to America. Some country clubs and gentlemens' meeting houses had indoor shooting galleries next to the bar for a bit more sport than darts could provide. And outside of the man's domain, silencers were marketed as being particularly suited to women, who's gentle disposition often found the thunderous din of gunfire to be off-putting, but an enjoyable garden pastime when properly suppressed.
(Notice that the advertizement from 1920 lists the base model .22 caliber suppressor for just $6, which today comes to about $80.)
And so it was that just like ordering any gun through the mail or buying your cocaine, heroin or laudanum at the corner pharmacist, freedom reigned, and suppressors were just hearing safety devices and nothing more. Sold over the counter at fine hardware stores, like plows, sacks of concrete, shovels and dynamite. Sure, like anything else, they were occasionally misused in crime, but there is a severe lack of documented history of criminal activity involving sound suppressors during the first 3rd of the 20th century, to the point it is impossible to claim they were any sort of public hazard.
Political upheaval and the perceived need to disarm the populace
Today we tend to think of the Vietnam War era as the model for tumultuous culture and change in America, but that's just because we are victims of comparison bias. Actually, the first 3 decades of the 20th century make the 60's and 70s look placid and stable. The burgeoning labor movements of the time, and the resistance to them, spurred violence and fear not seen since Reconstruction. While the leftists can be accurately said to have been the initiators of much of it, reactionary corporatist thuggery also contributed to it all, and acted often as merely pouring gasoline on the fire. Many mistakenly think of "The Old West" as full of violence, when actually as a dock worker or factory owner in 1920, you were far more likely to be killed by mob violence than having been attacked by indians on a wagon train 40 years before. And of course, the crime culture created by the government due to the 1st drug war, Prohibition, just added to it all. Law and order seemed a myth to many during those days.
Our first collectivist and anti-capitalist occupier of the White House, FDR, knew his ultimate plans for illegally altering America into something other than America could quite possibly result in another civil war if not managed carefully. As a result, some of his first articulated requests to his Attorney General, William Mitchell, were to formulate schemes by which the population could be disarmed. Beginning in 1929, several drafts were submitted to Mitchell for laws that would ban handguns and pistols and basically any armament other than hunting guns. The St. Valentine's Day Massacre had been salaciously kept alive in the news much of the year, despite not meeting the level of a massacre and significantly less lethal an event and lower in body count than many strike-busting battles had been. But to his credit, Mitchell was astute enough to realize no ban could ever withstand legal scrutiny of the courts and would be easily stricken down. He advised FDR and his aides as much. In fact, the FDR administration was desperate to find a means by which to pass laws to achieve their meddling with capitalism, which was not as easily achievable as he had promised voters it would be. But AG Mitchell's #1 contribution to FDR and knife to the back of Americans was his epiphany to reinvigorate the taxation and Commerce Clause authority. If guns could not be banned into oblivion,...perhaps they could be TAXED into oblivion. And by merely putting arms out of reach for the common man and the negro, the upper classes that really ran things would still have their guns, and the politicians their contributions.
As Congress began to change majorities in 1932 from Republican to Democrat, the various Commerce Clause based schemes FDR wanted began getting made into federal statutes. The first abusive taxation firearms bill, which in 1932 still sought to ban handguns, failed to pass. There were still enough members willing to abide the Bill of Rights to ensure its defeat. On the next attempt, however, in 1934, the National Firearms Act (NFA of 34') was tweaked to be slightly more palatable by no longer seeking to ban handguns, which the average American was simply too hostile to. Instead, the focus in marketing to get it passed was to frantically and breathlessly continually warn about the gang violence of organized crime, especially like that of the St. Valentine's Day Massacre. Although 2 machineguns were used that day (along with 2 shotguns and one pistol), there had only been a few instances in the past decade of gangsters purchasing machineguns and using them, despite what the movies tend to portray. Bonnie and Clyde stole theirs from the National Guard armories they burgled, as did Dillinger, who stole his Tommygun from the unlocked Auburn, Indiana police station. Most thugs of the day still preferred a revolver or shotgun. Just as facts don't matter in the gun-control supporter's mind today, neither did it in 1934. And never mind that Prohibition (which had birthed organized crime) had ended the year before. In an attempt to heap on the scary evil items that would supposedly improve the world by their absence, short-barreled shotguns and rifles, as well as bombs and grenades were included. And oh yeah,...those evil assassin tools, silencers. Although, if you read the official minutes of the debate in the House Committee on Ways & Means, you will receive no clue there as to why suppressors were included. The hearings never touched on gun mufflers/silencers at all; no reason was given for their regulation. It was only after becoming prohibitively regulated in 1934 that suppressors began getting portrayed in Hollywood and fictional crime novels as belonging to the realm of the assassin.
While FDR didn't get what he really wanted, he intended that the NFA of 34' would be the camel's nose under the tent and would allow him to later enact further gun control. And while he slightly succeeded with the NFA of 1938, which established that all manufacturers, importers and commercial sellers required federal licenses, the war in Europe changed everything. With England begging American cousins to send every spare personal handgun or rifle they could part with so as to fight off the expected German invasion,...civilian disarmament quickly evaporated as a legislative possibility. The Japanese sealed the deal in Hawaii in 41' and Alaska in 42'. Gun control schemes didn't become a popular idea with politicians again until the uppity negroes had the audacity to demand their civil rights, basing the Gun Control Act of 1968 of Hitler's anti-Jew gun laws of the 30s. (If you can't perceive the sarcasm in that sentence, just go home, kid.)
The NFA of 34' established that any of these items could still be bought and owned of course, provided that you paid a $200 tax and received an authorizing stamp as your receipt. That is equivalent to $3735 today! As a result, the legal suppressor market disappeared. Who was going to pay that sort of government fee for a $6 can?!
While still not an insubstantial penalty even today, at least the $200 tax has remained unchanged. As the inflation of the Carter era exploded, one small benefit was that the $200 tax stamp was more affordable, equaling in 1980 only about $650 in today's dollars. And as inflation has continued, the ability of the common citizen of all races to afford NFA-regulated items has slowly improved. And resultantly, legally-owned suppressors are more popular than ever before. More than 330,000 suppressors were registered nationwide in the two years ending in February 2016, according to the federal government. That amounts to about a third of all suppressors registered since 1934, when the NFA was implemented.
Things are different in Europe
As mentioned earlier, European legislators never considered sound suppressors to be inherently a criminal item or threat to society, and in fact, the best gun-owning citizens and neighbors considerately and conscientiously use them as often as possible so as not to be bothersome or disturb the peace. In places like France, Norway and Finland, silencers are sold over the counter without any onerous regulations or licenses, and are merely considered a hearing protection device. In England, where there are very few rifles other than little .22 caliber versions for harvesting small game such as squirrels (and even those are horrendously regulated and near impossible to acquire unless you are among the elites), hunters are REQUIRED to use suppressors, and can be fined and their guns confiscated if they don't!!
In the parts of Europe where suppressors are not so freely accessible, such as Germany, the concern is not assassins, but poachers. But as stated near the beginning of this article, 34 states find hunting with a can on your gun to be not worth prohibiting. The poaching concern seems over-blown.
And so, as people encounter and experience legally owned suppressors and their owners more frequently and commonly, the false myth of the dastardly assassin tool has more rapidly begun to fade from the minds of the general citizenry, replaced by the fascination of how nifty they really are. As this awareness has increased, so has the possibility that their inclusion in the stupidly onerous (and illegal) NFA regulatory scheme might be changed.
In 2015, Rep. Matt Salmon of Mesa, AZ. made the first real federal legislative effort to remove suppressors from under the NFA of 34' and treat them merely as any other firearm. This was titled the Hearing Protection Act (HPA) of 2016. While it seemed a lovely idea to us gundudes, hardly any of us hardcore gun folks expected it would go anywhere because we were so used to all the misinformation about suppressors, their nature and utility, as well as the fanatical religious zealotry the citizen disarmament block always exhibits. I figured it would die a quick and lonely death. To the amazement of many people like myself,...it actually received real consideration in Wash.D.C., and not just from the typical Republican pro-gun block,...but even several "centrist" Democrats. While it did still end up failing, it showed there was more potential for future efforts than many like myself would have previously believed, and the gun community was bolstered at the prospect of another future Hearing Protection Act meeting with success. When reintroduced in 2017 by Rep. Jeff Duncan of South Carolina, the next push began to experience even more positive reception than the previous congressional session. Trumps sons, who are members of the shooting community, made it clear that they vouched the old man would sign it if it made it to his desk. Gundudes were getting excited at the potential return of a small amount of common sense and freedom.
(Don, Jr. shooting a suppressed pistol in 2017.)
And then the Las Vegas Mandalay Bay concert shooting happened. Although no suppressor was involved, the lemming-like hoplophobes of the gun-control cult were inflamed and salivating to muck up freedom once more, and they made the vulnerable and delicate HPA their first target. The HPA was always going to be controversial, but libtards made sure it was absolutely toxic.
However, things change and time goes on. With the potential promise of sound suppressor freedom having been so close and nearly within grasp, those who wish to see it most have not given up. Who knows what the next Congress will do?
So how do I get one? What do they cost?
Until such time as suppressors get removed from under the NFA registry and are sold like your average shotgun, the process is sort of a pain in the ass. You can't just send in a $200 check. Along with that check, you are required to also submit a valid fingerprint card from a local law enforcement entity who prints you for this purpose, as well as a signature from a local law enforcement entity on your appropriate form attesting they are unaware of you having any legal disability to own a gun nor are under current investigation for any crime. You submit this package to the Bureau of Alcohol, Tobacco, Firearms & Explosives (BATFE,...also known alternatively as BATF or just ATF), and await for them to process your paperwork and notify you that you are cleared and good to go. That takes about 9 months. (And you thought the Department of Motor Vehicles was slow.) Upon getting your approval (complete with official tax stamp), the "transfer" of the suppressor to your possession can now occur. While you are awaiting the approval, your seller retains possession. NFA taxes are levied and collected upon every TRANSFER. You cannot gift or loan any NFA registered device, since that qualifies as a transfer. Your adult child can handle and use your suppressor while under your supervision and presence,...but if you wish to pass it down to them like a car or house, the transfer will require them to go through the process as well. (Bequeathing in one's will upon their death does not require the tax to be levied, but the fingerprints and law enforcement sign-off will still have to be performed, and the item held in custody by the executor. Few estate executors are experienced with this and it can be a mess.) Likewise, anyone who is not a prohibited possessor regarding guns can enjoy them while under your supervision and presence.
While the basics of suppressor technology are not a secret, many many makers have spent a lot of research and development time and money trying to achieve the ultimate in quietness. Some of these efforts have produced impressive results, while others not so much. But like anything else, specialists in this field can command a pretty penny for their products. If suppressor model A reduces a gunshot from 163 decibels to only 127 and costs $600, but model B reduces it to 123,...and costs $1000,...is that difference worth it? Only you can decide. But suffice to say that the state of the art of sound suppressors today has them quieting gunfire to levels lower than ever before. But how do you know which to choose?
For many years, as suppressor development and the civilian market grew, there was often a lack of standardized testing and evaluation procedures within the industry. Somewhat fortunately, during this same time period, various militaries in the western world were also increasing their interest in and use of suppressors in special operations. They began setting the testing criteria by which these devices would be judged, and by the late 90s, these standards were established. As a consequence, the suppressor market became much more Darwinian, with non-performers losing out on the government contracts. Unless their designs were inexpensive enough despite their less than leading edge, they failed in the private civilian market as well. But fortunately, civilian shooters usually don't require the BEST suppressor, whereas with commandos in enemy territory can find that to literally be a matter of survival.
In the internet age, I don't have to lay out all the models and prices and performance stats here. I can merely direct you to various forums where these matters are discussed, like www.silencertalk.com This is just an introductory article after all, but there you will find a time-sucking rabbit hole of data and opinions and reviews that could guide your purchase better than I ever could. You can also find there lots of illuminating info on who and where to shop from, navigating the federal process and much more.
And since the basic suppressor design is fairly simple, if you are handy with a lathe and metal fabrication, rather than paying for one made by someone else, you COULD just make your own rather inexpensively, beyond that $200 federal tax stamp. Many folks have.
But before you fabricate your own, be legal and get your forms submitted and approval back first, since the feds are evil bastards after all, and will happily throw you in prison if you don't. (Do I really need to say this?)
Solvent traps / suppressor kits
Perhaps you are NOT so handy at metal fabrication, and you don't know a lathe from a toaster oven. What then? Well, in recent years, your answer has come to be in the form of what is known as a "solvent trap".
You see, the BATFE, who is responsible for enforcing laws on suppressors at the federal level, are also empowered with limited ability to define beyond the actual statutes what is or is not a suppressor, a machinegun, etc. In that role, they have over the years tried to defeat attempts by creative folks who sought to get around suppressor regulation in crafty ways. In fighting this never ending ingenuity, ATF wrote those definitions and occasionally updates and rewrites them as expansively as possible to preclude anyone successfully doing an end run around the intent of the statutes. Thus, the guidelines ATF wrote for themselves was that ANY part of a suppressor that is specifically DESIGNED AS for use in or as part of a suppressor IS IN FACT a suppressor, and possessors of said things can be prosecuted unless they had been properly taxed, registered and transferred. Therefor, if you were to sell threaded aluminum tubes designed to attach to a weapon and serve as the main body for a suppressor, even though it was not yet completed into or yet function as a suppressor, ATF considered it a suppressor none the less. And people have been sent to prison for this.
Several different muzzle contraptions have appeared over the decades which have led to this. One of the most famous was an adapter which first appeared in the 80s that allowed you to screw on an empty 2-liter soda bottle. While perhaps the least effective or efficient sound suppression device ever marketed, reducing the perceived sound signature only slightly,...it none the less reduced muzzle blast by a plainly identifiable amount. Just shoot right through the bottle.
While only serviceable for 1 or 2 shots, you can't get any cheaper than that! But since it was obviously designed to act as an impromptu and disposable silencer, ATF declared these adapters to be actual ones.
A couple decades later, and some fellow improved on this idea a bit more by designing his to use automotive oil filters for trucks. While still having to blow an exit hole via the first round fired, these cans have a bit more resilience and last for many tens of shots before wearing out, and the cardboard filter material inside helps to deaden the sound better than the 2-liter bottle thing ever did. Costing only a few dollars, this was also very affordable. But didn't ATF simply declare it a suppressor as well, just like the soda pop bottle adapter? No,...and the reason is important.
The reason was because from day one, these were not marketed for use in sound suppression, but for an entirely different and legal purpose. They were said to be designed and intended for use as a "solvent trap",...to catch and collect noxious, oily and messy cleaning solvent, rather than to spill on your kitchen table or living room carpet. By threading one of these on the end of your gun, no more messy stains or nasty clean up. While perhaps a dubious claim,...it certainly COULD be used for that. And as long as the manufacturer never claimed in any way or attempted to market it as anything related to acting as a suppressor,...it was legal to sell and possess. Suddenly, these were selling like mad. Did anyone ever actually use these solvent traps for their stated purpose? Perhaps a confused few. The vast majority,...naaaaaahhhhh. Some folks even filed NFA paperwork on these and registered them as suppressors though, simply because at $20 plus the $200 tax stamp,...it was affordable enough to do so. You can still find them cheaply on the internet. https://www.guncleaningadapter.com
And herein lies where things really made the whole "solvent trap" market grow even bigger. When those few guys who registered the oil filter type of adapters with ATF, many small time fabricators realized it was now possible to market a do-it-yourself suppressor kit of a more traditional and effective baffle type as long as it was marketed as a solvent trap. This was significant because, remember that ANY part designed to be a suppressor WAS IN FACT a suppressor, according to the ATF's published regulations. But the solvent trap issue had shown that INTENT determined the fact of whether something was designed as or merely also useable as. Prior to this, the process of finding and buying components to legally build your own suppressor was fraught with legal danger. The common work around was a semi-black market of custom colored anodized Maglight flashlight tube body "extenders", with thread types suitable for the stated purpose. Automotive freeze plugs of D-cell battery size were modified as baffles and extra end caps were also sold. But now, these same items, rather than being sold separately were now bundled in a package as a "solvent trap kit", being practically an entirely completed suppressor, needing only the front end cap and freeze plugs drilled. But it wasn't. It was/is a solvent trap,...wink wink.
Suddenly, you could buy a solvent trap kit and perhaps a few other items, and after getting your ATF approval to build it, you could now build a REAL and rather effective performing true baffle-type suppressor. And for a LOT less money. The oil filter adapter things, while still available, dropped in popularity very quickly, and in no time at all, the D-cell sized Maglight body type solvent traps were for sale all over the internet. They still are. https://solventtrapsdirect.com This is one of those "don't ask, don't tell" type things.
Let's be clear;...ATF absolutely HATES this. They are after all in the business of destroying freedom and the Bill of Rights is just a goddamned piece of paper. So they didn't take this laying down, and intensively surveiled various online sellers of these solvent trap kits so as to try and find a way to raid them and shut them down. They had a few limited successes, but these sellers are aware of the fine line they are walking and are careful not to cross it.
A Brief Overview Of The Mechanics Involved
While I mentioned earlier that slowing the propellent gas from exhausting out into the atmosphere is the principle by which gunfire is quieted, and that flow-retarding baffles are the most common way this is achieved, that's like saying cars utilize internal combustion and use gasoline. There's much more to the story than that.
While simple straight 90 degree angled baffles like those of a hardware washer work fine, Flow Dynamics 101 informs us that the task of the gas fitting through the bore hole is made more difficult (and therefore takes more time) if the chamber wall is of a cone style.
Although Maxim's original design utilized baffles formed in a manner that was hoped would scoop gas to flow outwardly against the inner tube wall like a swirling smoke ring. Nice idea,...but in the days before computer modeling and slow motion photography, this theory seemed valid.
Eventually, someone tried to meld the best of both baffles into a cone baffle which had spiral grooves which attempted to swirl the gas into a vortice and use the gas' own velocity to temporarily keep it "pinned" to the inner wall of the tube.
Another development was to take the somewhat standard cone baffle and cut an uneven orifice for the bore hole. The intent was that by doing so, the gas would unevenly flow and thereby create vortexes which would impede flow into the next chamber even better. This is known as a "clipped cone" baffle, and has proven to be one of the better adaptations.
All of these are designed to be independent baffles that would be inserted into a tube and sitting on top of one another,...often referred to as a "baffle stack". And as long as these components – the tube, the baffles, end caps and any spacers – are all machined and/or fabricated with close and tight tolerances so they fit snugly and tightly, and are used only with relatively low pressure pistol calibers,...things tend to work well. Trouble, however, tends to become a greater possibility as pressure and power of calibers involved increases. For instance, a .22lr cartridge operates at 22,000 psi, as does even the large .45acp, which was designed around the time Maxim invented suppressors. The common 9mm cartridge, designed only a few years later in 1909, operates at 35,000 psi, but is still easily manageable by the average baffle stack type of can. Rifle calibers, however, are an entirely different level of pressure and gas volume produced when fired. The common .223/5.56 round fired in the M16/AR15 series of weapons operates at 55,000 psi, and about triple the volumetric gas produced upon firing than the sedate 9mm. The .308/7.62 used in many battle rifles operates at 60,000 and about double the gas volume produced than the previously mentioned .223/5.56 All of this is to say that a perfectly resilient design when used with a pistol may not withstand use with a rifle or carbine.
When things do go bad inside a suppressor due to over-stressing a baffle stack not sufficiently engineered to handle greater pressures, weird and catastrophic results can happen. It is possible under the right circumstances that a baffle can twist or turn within the suppressor sufficiently enough to cause a passing projectile to impact it rather than pass through without touching anything. Known as a "baffle strike", it can be the slightest glancing scrape that results in nothing more than a mark on the orifice of the baffle in involved, or in a worst case scenario, it can cause an explosive disassembly of the suppressor, with pieces flying everywhere.
The cause can be too thinly constructed a tube to contain pressure without deforming, and/or radically increasing heat stress of the tube and components from sustained fire, such as with a machinegun, also causing stretch and/or deformation.
While aluminum is the most widely used material, using steel can resolve some of these issues. But due to weight, titanium is often preferred instead. 2 solutions that have become very popular in the last few decades are "sealed units"; steel or aluminum suppressors with each baffle fully welded permanently in place and the entire suppressor welded or "sealed" shut;...and "monocore" one-piece baffle assemblies, usually machined from a single solid aluminum billet.
Monocore suppressors have rapidly become popular not just for rifle-rated cans, but even for the lowly .22 plinkers, primarily because disassembly, clean-up and reassembly are much easier with these. Sealed cans tend to be government contract models because they cannot be disassembled for cleaning and are considered a disposable consumable with a limited service life of only so many rounds before being replaced. But for citizens who have to pay out the nose for these things and jump through all the regulatory hoops, sealed units are usually not an attractive option. Most civilian American consumers would prefer that they could clean and/or replace components, and thereby enjoy their muffler for many years or decades. So monocore designs are rather popular now.
Another phenomenon with suppressors that can be pesky when using auto-loading rifles like an AR15 is back-pressure. Since, after all, a suppressor slows down how fast the escaping gasses release, this means pressure is actually retained slightly longer. If an automated action begins unlocking and cycling very soon, this can result is more rearward escaping exhaust gas to the shooter's face than otherwise would occur. This acrid smoke can sting the eyes and make them water, and/or can irritate the lungs. In strings of rapid fire this can be common. Pacing the rate of fire in such a way as to not gas the shooter can be rather important. On rifles with adjustable gas settings, it is often suggested to use the least amount of gas bleed off as possible when utilizing a suppressor, to attenuate this condition.
A neat trick the Navy Seals noticed many decades ago is that trace amounts of water inside of a suppressor enhance performance and reduces sound even further. This occurs because the water gets atomized under the internal pressurization and becomes steam rather instantly, cooling the temperature of the gasses a bit. This small temp reduction affects the sound by a couple more decibels. Don't allow so much water inside the suppressor that a projectile might be impeded. But in most baffle stacks inside a suppressor, there will remain a tablespoon or two even after attempting to drain a flooded one. Depending on the power of the caliber being fired through the suppressor, it might take only 3 to 7 shots to fully atomize and evacuate the remnant water. But at least for those few shots, your suppressor will be quieter than if left dry.
Special Adaptation Required For Use On Most Auto Pistols
Ok, so lets say you decided to get a suppressor for your Glock. You've done everything legally, you acquired a special threaded replacement barrel for which to use it with and mount the suppressor on, and now you just screw the thing on and we're ready to rock, yes? No,...not quite yet.
Like the Glock, most other auto-loading pistols are known as "locked breech" designs or alternatively "delayed blowback", describing essentially the same principle. What this means is that both the slide AND the barrel move rearward together initially during the cycling of the action when fired. Usually only ¼ inch or less, at which point this rearward momentum is used to cam the barrel locking lug out of its recess in the slide. Once this occurs, the barrel is no longer coupled with the slide and stops moving, while the slide continues its rearward travel and cycling. However, when one hangs a bunch more metal out on the muzzle, this changes the carefully engineered and mathematically calculated relationship of the moving parts in the pistol. The recoil spring is designed to function with a certain amount of mass. That mass has now increased due to the addition of the can hanging off the front. When fired, this usually results in the pistol either not unlocking at all, or if it does, so much energy is expended moving the larger mass that the slide does not travel sufficiently far to the rear and "short-strokes". Either condition results in failure to feed the next round, and the pistol is no longer an "auto" but merely a manually-operated repeater, requiring you to jack the slide to the rear each time in order to shoot again.
For decades, this meant that only pistols with a fixed non-moving barrel could be adapted to feed and function with a suppressor attached. This limited one's options to only a handful of pistol designs, usually in rather weak calibers. But only about 25 years ago, a Finnish gentleman by the name of Neilsen devised Linear Inertial Decoupler (LID) device that changed everything. These popular enhancements for most modern pistol suppressors are known by a few names, including Neilsen Device, LID, recoil booster or muzzle booster. They all consist essentially of a spring-loaded piston cup inside a piston chamber. The piston threads onto the barrel and the unit itself threads onto the suppressor. When the propellant gas enters the interior of the device, it propels the piston rearward, imparting an additional recoil impulse to the pistol sufficient to overcome the taxing additional mass that would normally induce a stoppage of the operating cycle. As well, this allows the suppressor itself to essentially stall in place rather than move rearward, freeing its mass from that of the actually recoiling mass.
These boosters work not only for sound suppressors, but many other things you might want to attach to your pistol, like say,...a golf ball launcher. Because they can function with items other than silencers, and are not exclusively designed only for that purpose, Neilsen devices are available over the counter for about $100. https://sdtacticalarms.com/-Booster_p_151.html
Aside from the escaping high pressure exhaust creating the boom, gunshots also make noise in a completely separate way. Any bullet which breaks the sound barrier also produces a noise event separate and independent from the escaping gasses of the gunshot, and there's nothing a silencer can do about that. These supersonic projectiles create a mini sonic boom, just like a fighter jet, though not nearly as loud.
Thus, there is a big difference in quieting performance between subsonic (slower than speed of sound) and supersonic (faster than speed of sound) ammunition within the same caliber. For instance, in the very common 9mm cartridge, most ammunition in this caliber throws a 115-124 grain bullet at about 1100 to 1200 feet-per-second (FPS), which is supersonic. But this caliber is also available with heavier projectiles, usually 147 grains or heavier, traveling subsonic, at about only 1000 fps, or less. Careful selection of your ammo will produce either quieter or louder results.
As a result of this fact, some pistol calibers that are almost always subsonic have often been the preferred choices for suppressing handguns. Those calibers are;
.32 a.c.p.(Automatic Colt Pistol)
These calibers are also old in design, and operate at lower PSI than more modern ones, which makes suppression slightly easier. However, 2 more modern calibers that are favorites despite their higher pressures and occasional supersonic loadings are the previously mentioned 9mm and the .40S&W. As well, the smaller the bore diameter, the easier it is to trap, restrict and suppress exhaust gas and noise. The larger the bore, the more difficult the task. Yes, the .45 is a low pressure slow-moving round,...but that hole. Damn that large hole!
For these reasons, .22 and 9mm dominate the pistol calibers most often chosen to be suppressed. The .22 tends to not only be the quietest, but it and the 9mm are also among the cheapest to feed. Economies of scale in production and demand make it so.
Some manufacturers turn out subsonic ammo specifically marketed for users of suppressors. There is also usually a small premium in price. If one knows their ballistics tables, it is not entirely necessary to shop only for ammunition marked this way, but it does make it simple.
Time To Bust Some Myths
As I mentioned earlier, there are a lot of misconceptions about gun mufflers. Probably the biggest is how quiet they are portrayed as being. I said at the beginning, the proper term is suppressor, because they suppress the gunfire, not silence it. Those movies where the only noise they make is a quiet pew,...balderdash! Now we should really emphasize that some little calibers suppress rather well compared to their bigger bore brothers, and that can make a big difference,...say like between a .22 compared to a .45! But no gun can be truly silent, although some combinations come close.
The first element of the myth of how quiet suppressors supposedly are which Hollywood never bothers to show is that there is a HUGE difference perceived by the human ear indoors vs. outdoors when a suppressed weapon is fired. Earlier I used the term Sound Pressure Wave. Remember that gunfire noise is a result of the gas entering the atmosphere. It is the sudden release of pressure which causes the sound. While the suppressor slows that speed down, the pressure is still released, and transits the atmosphere in a wave form. Inside the confinement of a house or other building, that pressure wave will bounce off walls and reflect. Without an easy exit, the wave is amplified within the confines of a structure. Thusly, a suppressed weapon that sounds rather quiet from only 5 feet away outside will be perceived to be much louder in a hallway or living room. While someone in an adjacent apartment might not realize they heard a real gunshot and might think they only heard one on a TV with loud volume,...the sound is not eliminated. Even outside, while perceived noise level is reduced from that perceived inside, the suppressor is not noiseless.
In fact, even the measurements by which suppressors are compared can be erroneously misinterpreted. Above is a chart showing the degrees in decibels by which various calibers are quieted when used with a suppressor. It shows, for instance, a 9mm handgun being reduced from 162dB to 126dB (on average). Many people make the mistake of using simple linear mathematics and saying "Well that's only a reduction of about 25%. That doesn't seem very much." On paper, no, it doesn't. But just like the Richter scale for earthquakes,...the scale is not a straight line experientially. Not only at the source, but especially as distance increases. That unsuppressed pistol can be heard for hundreds or thousands of yards in open terrain, but the suppressed one won't likely carry even 100 yards. That's a reduction of actual effect far greater than 25%.
The second most common myth is when Hollywood depicts a suppressed high-powered sniper rifle as being as quiet as a suppressed handgun. (Cue the wrong answer buzzer here!) Almost any true rifle caliber will be throwing its projectile at faster than the speed of sound.
The sonic boom of an object flying greater than the speed of sound is in relation to the size of that projectile. So a little .22 caliber bullet makes a loud "crack", while a .30 caliber makes a slightly louder but similar noise, like a small firecracker. The booming muzzleblast will be reduced of course. But the suppressed sniper rifle will always be at least as loud as an unsuppressed .22 squirrel rifle. If you've seen the movie LONE SURVIVOR about the ill-fated Navy Seals mission in Afghanistan, this is one of the only movies to ever get it right.
The third most common myth, and one of the oldest, is silencing a revolver. Ung! Hard to believe this is still a thing, but here we go. Revolvers have a small and thin but open and clear space between the front face of the cylinder, where the cartridges are contained, and the barrel the bullets are propelled through. This is called the "cylinder gap". When a round is fired, the bullet jumps from within the cylinder chamber that is currently inline with the barrel, and travels across this gap into the barrel. The hot expanding gasses of the gunshot also do so,...but because of the gap, some escape out to the sides of this gap. As a result, no matter how efficient a design of suppressor you might hang off the end of the barrel, it will do nothing about the blast noise generated by the gasses escaping out the cylinder gap.
While there is at least one revolver design out in the world which operates a bit differently and CAN be suppressed, the vast 99.9% of revolvers in the world are non-suppressable. They will always be loud.
Also, the movies sometimes make it look like sticking a silencer on a gun is fairly easy,...as if any weapon will accept one on the end of its barrel. If you go by what the TV depicts, a silencer just sort of spins on or into any barrel somehow. Nope! The individual weapon must be specifically made at the factory or later altered to mount a suppressor. While today it is easy to simply mail-order a replacement barrel unit for this purpose, decades ago it could be difficult to have a barrel custom manufactured for you with a bit of extra length which you would have a gunsmith cut threads on for you. And your suppressor needed MATCHING threads, which could easily complicate things. Ever shop for nuts and bolts in a hardware store? They don't all match, do they. In decades past, many suppressors tended to me mated to an individual gun, since it may not fit the thread pattern of any other. While today there are fewer thread pitches (patterns) utilized for weapon muzzles and there has been a growing industry standardization as to which thread pitches best serve which calibers,...the problem has not entirely gone away.
At least in America, thread pitches for .22 through 9mm bores are now all usually 1/2x28 inch (with the exception of .30 caliber rifles which now mostly use 5/8x24), while .40/10mm bores are usually 9/16x24 inch and .45 caliber are .578x28 inch. And of course, they are all clockwise twist to tighten. (The first number refers to diameter, while the second is how many threads per inch.) But imported guns from Metric countries can be entirely different, with 9mm caliber threads usually being 13.5x1mm with a counter-clockwise twist, for instance. Got that? Yeah, probably not.
Another thing Hollywood doesn't tend to show is that suppressors get HOT.
Ever accidentally touched a muffler on a running vehicle? OW!! After firing a dozen rounds or so, it might be rather difficult to try to unscrew one with your bare hands. Whether made from aluminum or steel or other metals can affect heat retention. Aluminum tends to cool fast, but also heats fast, too. Many folks have tried to devise burn-prevention coverings for suppressors, usually involving Nomex, which is a flame-resistant synthetic material used in military flight suits and tank crewman coveralls. Also various silicon material attempts have been tried. Two of the better ones are made by MANTA and KOOLHAND.
Rifles tend to heat up suppressors more quickly than pistols, because rifles use more propellant. That means more burning fuel, so to speak. Little .22LR guns, whether pistol or rifle, tend to heat up the slowest because .22s use the least amount of propellant. Less gun powder, less burn, less heat. (Also, .22s are the easiest to quiet, since they aren't very loud to begin with.)
There is much, much more to owning and using sound suppressors than most folks realize, and I have only scratched the surface here. But perhaps this has intrigued you to investigate further whether one of these (or even several) are for you. If nothing else, hopefully I have demystified some of this and dispelled a few myths. Remember that these are merely gun mufflers,...without any inherent evil, despite what others would have you believe. They are safety devices and make for good neighbors.
Keep aware of the future bills that may help to eliminate the stupid and onerous over-regulation of suppressors, and share with your friends and family the real (lack of) history behind their unjustified demonization.