Mitchell WerBell Silenced the U.S. Army’s M-14s and M-16s

Uncategorized April 7, 2016 0

The SIONICS suppressor proved very reliable by MATTHEW MOSS In the early 1960s, former U.S. Office of Strategic Services operative Mitchell WerBell III founded a company...

The SIONICS suppressor proved very reliable


In the early 1960s, former U.S. Office of Strategic Services operative Mitchell WerBell III founded a company dedicated to the development of cheap and efficient sound-suppressors for automatic weapons.

Following the Japanese attack on Pearl Harbor, WerBell had joined the U.S. Army, serving briefly as a second lieutenant with the Signal Corps before volunteering to join the newly-formed OSS in 1942.

WerBell became an expert in guerrilla warfare. He fought in Manchuria, Burma and Indochina, during which time he became familiar with the suppressed firearms that often featured in clandestine missions. After the OSS disbanded in September 1945, WerBell returned to the regular Army as a captain, but complained that the routine of commanding an infantry company was dull and soon resigned.

During the 1950s, he worked in public relations and advertising before deciding to launch his own manufacturing company specializing in suppressors in 1966. The company’s name SIONICS stood for “Studies in Operational Negation of Insurgency and Counter Subversion.” WerBell himself designed suppressors for the M-16 and M-14 and applied for his first patents in January 1968.


SIONICS also adapted existing firearms to be compatible with suppressors. Guns the company so modified included High Standard pistols, Remington bolt-action rifles, Ruger 10/22s and Smith & Wesson M76 submachine guns.

The SIONICS M-16 suppressor featured a tubular housing filled with a series of entry, suppression and resonant chambers. The suppression chamber contained sets of helical metal baffles rather than the traditional wipes. It attached to the rifle’s muzzle by way of internal threads.

A suppressed M-14. Photo via the author

A stepped, axially-apertured partition separated the suppression chamber from the entry chamber. The suppression chamber was ported to allow propellant gasses to enter the helical baffles. The design’s baffles were inside the housing, alternately opposing each other in order to prevent the free-flowing of the captured gases.

The patent explains that the suppressor’s housing varied in thickness in an effort to further deaden sound vibrations. WerBell’s patent also states “that more than five suppressor units [the helical baffles] may be used if desired” to increase the suppressor’s effectiveness. The patent notes, however, that testing with just two oppositely-wound baffles achieved satisfactory results.

Interestingly, WerBell’s second patent mirrors legendary gun-designer Hiram Maxim’s own work in one weird way. It claims the suppressors could work as “silencers for use in conjunction with firearms and as mufflers for internal combustion engines.” This second design includes some entry chamber variations but retains the helical baffle system.

WerBell’s third patent, which he submitted in December 1970 and which the government granted in January 1973, incorporates a relief-valve system to reduce blow-back pressure when fitted to rifles and machine guns chambered in 7.62-by-51-millimeter.

Designed for the M-14, SIONICS’ M14SS-1 was 12.75 inches long and 1.7 inches in diameter. It weighed just under one kilogram. The early production models used the patented valve system, but these suffered failures owing to the valve acting as a heat sink and melting the valve’s spring. The valve couldn’t withstand the high gas pressures and WerBell eventually designed a simpler relief port.

The M16 (Weapon)

The U.S. Army purchased the majority of the SIONICS M14SS-1s, but the Navy also bought a few.

Forty M14SS-1s went to the 9th Infantry Division in Vietnam for combat evaluation in 1969. Encouraged by the results, SIONICS also developed the Moderator Automatic Weapon-Alteration 1 for the M-16. U.S. Special Forces in Vietnam carried these suppressors on long-range reconnaissance patrols and clandestine missions.

The MAW-A1 initially included the patented relief valve, but issues with the M-16 compelled WerBell to add a more reliable relief port. The MAW-A1 proved to be a reliable and effective design, well-liked as it was rated for full auto fire. Many of SIONICS’ suppressors had a rated lifespan of six months or 200 rounds before the suppressor’s efficiency began to deteriorate.

At this point, the shooter could take apart the suppressor and replace the helical baffles and other internal components. SIONICS also developed a series of pistol silencers, which U.S. Special Forces adopted and often paired with High Standard or Ruger .22LR pistols or Smith & Wesson’s Model 39.

This post originally appeared at Historical Firearms.

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