Tuesday, September 5, 2023

Prepper's Armory: Suppressors

Hiram Stevens Maxim is probably best remembered by the firearms community as the inventor of the Maxim Gun, the first effective and reliable true machine gun. However, in addition to his many other inventions and achievements, Hiram Maxim did something else: in 1869 he fathered a son named Hiram Percy Maxim.

Like his father, the younger Maxim was also an inventor of note, with a number of designs and patents to his name, including the subject of today's post: the silencer. Perhaps I should call them suppressors, mufflers or moderators as these devices soften, but do not completely silence, the report of a gunshot. Regardless of the proper terminology, however, Hiram Percy Maxim called them silencers, creating the Maxim Silent Firearms Company in Hartford, Connecticut in 1908 while waiting for his patent to be approved. In 1912, he incorporated the business as the Maxim Silencer Company.

However, I'd prefer to focus on the technology itself. In patent number 916885, issued on March 30, 1909 and titled "Silent Firearm", Maxim described his invention as:

"A silencing device for firearms, comprising a supporting shell or casing and a series of diaphragms or spreaders disposed in said shell or casing and forming therein a succession of chambers, each of such diaphragms or spreaders having an opening for the passage of the projectile and for the escape of the gasses from each chamber into the next and from the last into the atmosphere."

Detail of Silencer from Maxim's Patent

Allow me to rephrase this in modern English: after the bullet passes through the suppressor, the propellant gasses are diverted by these diaphragms and fill the chambers, both slowing and cooling said gasses, until eventually they exit the suppressor, reducing the audible volume of the shot by varying degrees.

Current terminology calls the diaphragms or spreaders baffles and the chambers are called expansion chambers, and units with different shapes, numbers, and sizes of both chambers and baffles are regularly designed in an attempt to reduce weight and improve efficiency. See the list at the bottom of this article for more information.

Early silencers had some notable differences from the devices we're generally used to today. First, Maxim's original silencers were designed with the bore axis off center from the tube, which meant the mass of the silencer hung below the line of the barrel, allowing the use of factory iron sights. With few exceptions, most modern suppressors are concentric to the firearm bore and require either a raised optic, or special suppressor-height iron sights.

The second difference is the internal arrangement of expansion chambers. Maxim's silencers were designed to direct the escaping gasses in a particular manner. In his own words:

"They [meaning the gasses] are made to dissipate their energy by being given a rotary or whirling movement in a suitable chamber, the velocity being so great that the gasses are held by centrifugal action against the wall of the chamber until by friction against such wall the velocity is gradually retarded and the gasses are permitted to escape gradually through an opening."

This design, while effective, is more complicated and therefore more expensive to produce. Simpler, but nearly as efficient suppressors are available on the current market.

Two of the author's auppressors

One thing to keep in mind is that suppressors are not like what we hear in the movies or on TV. They don't reduce the sound of a gunshot to a soft thud; it's still clearly a gunshot, and it's generally uncomfortably loud at close range or indoors. While suppressors can potentially reduce the noise of a gunshot by up to 35 decibels, about as much as quality ear protection, the resulting volume is still frequently above 130 decibels. According to OSHA, 140 decibels is the danger level where immediate, permanent, hearing damage occurs. 

The most efficient suppressors, on the smallest and quietest caliber firearms, generally only reduce the sound of a gunshot to between 110 and 120 decibels. For comparison, fire engine and ambulance sirens are generally in the 120 decibel range. The ability to suppress a firearm to truly comfortable hearing safe levels is more of a challenge than most people realize.

Same suppressors mounted on different firearms

In addition, any projectile that exceeds approximately 1,125 feet per second will still break the sound barrier and create a sharp crack when fired. This is why special subsonic ammunition is available for shooting suppressed firearms, generally pushing heavier bullets at lower velocities, such as 147 grain 9mm and 200 grain .300 AAC Blackout.

With the development of additive machining and improved materials technology, modern suppressors can be more efficient and lighter than their predecessors. There are a number of suppressor companies offering a wide variety of units in different calibers, styles, and price ranges. 

The only reason suppressors aren't more common and less expensive is legislative. Thanks to the National Firearms Act of 1934, those wishing to purchase or construct a suppressor must first send an application to the Bureau of Alcohol Tobacco Firearms and Explosives. This includes submitting notarized forms, fingerprints, informing the chief law enforcement officer in the applicant's jurisdiction, and a non-refundable $200 fee.

While wait times can vary considerably, eight to nine months seems to be fairly common. My last suppressor application was submitted in early December of last year, and was finally approved in early August of this year, for a total of about 250 days.

Currently, private possession of suppressors is legal in 42 states. However, they may not always be legal in every municipality in those states. In addition, suppressors can be used for certain types of hunting in 41 states. For those interested in contributing to the fight for greater suppressor liberty, I highly recommend making a donation to the American Suppressor Association.

Whether they're called silencers or suppressors, mufflers or moderators, these beneficial firearm accessories should be inexpensive and readily available to all shooters. Hearing damage is cumulative and permanent and will eventually affect us all.

Have fun, and safe (and quiet) shooting.

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