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G&A Basics: How Suppressors Work

by J. Guthrie   |  May 13th, 2012 13


They are the darling of Hollywood directors trying to make assassins more sinister, and no SEAL or Delta operator’s rifle is complete without one hanging off the barrel. Silencers—or suppressors, or cans—have hit the mainstream, and it might surprise you to know that silencers predated “talkies” and civilians, mere mortals like you and I, can own suppressors—not just military guys and law enforcement officers.

Hiram Percy Maxim, son of the dude that made belt-fed machine guns mainstream on battlefields across Europe, is credited with bringing the first silencer—his name—to market in the early 1900s. It seems everything about silencers, from what to call them to owning one to understanding how they work, has gotten more complicated as time marched on. Here is a primer on what they are, how they work and how to get one.

Probably in the interest of selling more silencers, Maxim stretched the truth a bit when it came to effectiveness. Silencers do not make guns silent but can greatly reduce the noise, depending. A more accurate term and one used most often by the American firearms industry is suppressor. I like “can” because it’s short and sweet like a midget that hands out candy. The rest of the world calls them moderators or mufflers.

The Science
Guns make all kinds of noise when fired. The firing pin striking the primer makes noise and the action cycling makes noise, but the really big “boom” is produced by the bullet breaking the sound barrier, and the propellant gases exiting the bore at supersonic speeds and shredding the surrounding air. Those propellant gases account for most of the racket and all of the flash.

A suppressor simply contains the burning propellant gases, capturing that energy. Most suppressors are made up of a series of small chambers separated by baffles. Manufacturers use all sorts of angles, ports dimension changes and other tricks to give the propellant gases a chance to spread out and shut up.

Just how effective is your average suppressor at quieting your average gunshot? Plus or minus, gunshots run 160 to 180 decibels. A good suppressor will trim 20 to 40 dBs off that signature and often make gunshots “ear safe” according to government standards. The bigger the suppressor, generally speaking, the better it will be at quieting guns.

Shooting subsonic ammunition and locking an action or shooting fixed breech firearms are other ways to lower the decibels, but both come with their own set of tradeoffs. I have shot suppressors that were Hollywood quiet—you could literally here the firing pin smack the primer and the loudest sound was the bullet hitting the target. But those gun/suppressor/ammo combinations are pretty limited in range and power.

Given that propellant gases are hauling ass out of the bore, suppressors have to be tough. Most are made of steel and high-tech alloys and every seam is welded. The best cans, like models from SureFire and AAC, are rated for full-auto fire and thousands and thousands of rounds. They are also expensive. Smaller cans meant for .22s can get away with aluminum components.

What’s the big deal if silencers don’t actually silence guns? The military loves them because they allow combatants to better communicate on the battlefield and retain their hearing, short-term and long-term. Suppressors also make it harder to find someone shooting at you by reducing the noise, dust and flash. If you are doing the shooting, that is a huge advantage. Hunters and recreational shooters can save their hearing and make shooting more enjoyable by making shots ear safe. Suppressors also reduce recoil to a degree.

Hang It
How do you get that suppressor on the end of that rifle or suppressor? This is the easy part. Suppressors can be integral, built into the barrel. Most use threads or a muzzle device to attach and detach. I really prefer the muzzle brakes that double as an attachment point because they are solid, make taking the suppressor on and off super quick and, in my experience, have less of an impact on accuracy and point of impact shifts.

Buy It, Sort Of
Now that we know the how’s and why’s, it’s time to buy a suppressor. If you lived in Scotland, they would be required for hunting. If you lived in Finland you could saunter down to the local gun shop and buy one over the counter—one more reason to like Finland. In the U.S., suppressors are regulated by the National Firearms Act and you have to first make sure they are legal in your state, fill out a federal form and send it, a couple of photos and some fingerprints into the BATFE for approval. Once approved—the process can take six or seven months—the BATFE sends you a little stamp and some paperwork and you can take possession of the suppressor from you dealer. There are legal considerations for interstate transportation and transferring the suppressor too.

One of the best online resources covering suppressors, CanU: The Silencer University, was put together by AAC, one of the country’s leading suppressor manufacturers.

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  • Joe

    From hear to they're, or righters have four got ten there English…

    • jkarczmit

      Thank you. I concur. You would think that there/their/they're might be an editor looking these articles over, but every magazine is full of gramma mis-steaks. Jezz, you got me doin' it!

    • Bill 4F

      It is disgusting! You can't read the newspaper without having to interpret some of the "English". Even editorials (which should have been proofed by their "professional", "paid" writers) are fraught with mistakes.

  • Bill K

    I would love to have a couple on my varmint/hunting rifles for the noise pollution/reduction on the ears and surroundings in general. But being in Kalifornia that will never happen.. Politicians are to in tune with the gangster theory and silencers.. to allow citizens to own them.

  • Joe

    …and James Guthrie, U-Can haul you ass out of the editor's office for bad English.
    Just "neat-picking" ;-)

  • don

    The author forgot to mention a little thing like the $200 that must be sent with the paper work to the feds!


    • Paul

      but its the same price as it was 60+ years ago

  • Cobus

    I agree with the Editor. No matter what the cost. All of my rifles, except the the .458's are fitted with suppressors. It makes a hell of a difference when hunting in the African bush. The proof of this is that the rest of the herd stands quietly and calm even after one of the herd has fallen. Or shooting on the range. I even fitted one to my Uzi, for home defence and it is totally quiet. The only point I disagree on is the muzzle break. It is OK for the shooter, but the poor schmuck standing next to him feels the pain.

  • Beau

    The author acts as if simple paperwork is all that's needed. Bureaucracy at it's finest, you say? That is clearly not he case. There are strings attached, and hefty fees as well. Better to get a .22 with sub-sonic rounds and build your own can. For an average Joe, 200$ + a moderate google search = silenced ruger 10/22 (there is not much skill involved, you can literally shoot off the edges if it's not perfect. The baffles are what is important). The result is an accurate rifle as quiet as a bb gun. All you can hear is the brass plinking on the pavement. Larger calibers take more work, and if the round isn't sub-sonic you will hear it. You don't need to silence your .223, but it would be cool… And you may not need hearing protection, so there's that.

  • a Finn

    Suppressors have been a regulated item in Finland since summer 2011 – in theory.
    If you have any firearm permits you don't have to do anything but buy the suppressor you want, but people without registered firearms now have to get a separate permit to buy suppressors. Another useless law. There is no legal precedent yet about airsoft/air rifle suppressors and the law is very vague about what a suppressor is. Another thing: it's legal to MAKE a suppressor without owning a firearm or a license.
    Probably the reason for these kinds of vague carte blanche laws is to make it possible to sue anyone, anytime, for something made up on the spot.

  • Starky

    Also be sure to keep a copy of your paper work with you when using the silencer. You can also expect a very long wait once you have filed out the paper work and paid the $200.00 to the Feds. six months at least. Currently I am waiting for one of our local firearms dealers to get the ok from the Feds. to sell silencers. He has been waiting close to a year now and still waiting.

  • David Kachel

    Great leftist frightening devices. They don’t even need to work. Just the scary look makes them wet their spanks.

  • Bill Piper

    Had a special make-up for me back in the 70’s. Was a service .45 with a extra level to lock the action and with sub-sonic ammo was very effective an close range. And yes, Hollywood quiet. Really a very special purpose firearm, I used it for fear the night and recovery work during Vietnam.

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