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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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