First of all, a clarification: we determined the volume levels with a commercially available, mobile measuring device, and not in the laboratory for Corona-related reasons. Therefore, measurements under laboratory conditions may show slightly different values. Also, laboratory devices measure the extremely fast increase of the volume level more accurately, microphones of simple devices are not sufficient for this. Subsonic cartridges for pistols, however, have strongly deviating ballistic conditions compared to hunting cartridges. These allow a simpler approach. The comparability of the values among each other is therefore always guaranteed, for the specifics of a silenced handgun, the simple test setup is completely sufficient.
The Beretta M9A3 in 9 mm Luger
The M9A3 is a follow-on model to the Beretta Model 92, which was introduced into the US Army as the M9 beginning in 1985. With a relatively simple design using a falling-block locking sytem, Beretta has delivered more than one million pistols to US armed forces and law enforcement agencies. The M9A1 followed in 2006, and the M9A3 was introduced in 2015. The most striking feature is its straight grip – the Vertec version. Its shorter distance from the back of the grip to the trigger blade satisfies short-fingered users and women. An included one-piece wrap-around grip, covering the back of the frame, provides a secure grip for medium and large hands.
The A-Tec PMM-6 Silencer
The A-Tec PMM-6 contains a spring-loaded piston, which acts like a recoil amplifier. Thus, the A-Tec PMM-6 prevents the occasional malfunctions caused by silencers on short-recoil operated pistols. The recoil amplifier should be removed, cleaned and lubed after 300 rounds. The number 6 in the model designation stands for the six modules of the silencer. Unscrewing one module, in addition to the length, decreases the noise attenuation performance too. The last module features a crown-like design.
A-Tec PMM-6 silencer specs and price
9mm Luger (9x19 mm)
Stainless steel, aluminum
|Weight: ||7.58 oz/215 g|
LH or ½" - 28 UNEF or M13x1 |
|Notes:||1 = The
damping performance is an average value, the respective damping depends on the
humidity and temperature. 2 = Without the addition of some water as recommended
by the manufacturer. 3 = Omission of modules possible. Replacement modules cost
about 60 euros each. 4 = Variable, depending on the number of modules.|
Robert Riegel with the Beretta M9A3 with silencer on the shooting range
In addition to the acoustic ones, the differences in kinetic impulses when shooting also stand out, i.e. less flip and recoil. The silencer acts like a barrel weight. Under hearing protection, the slide noise seems louder than the shot itself. We determined about 73 dB for the slide noise only. The measuring device was placed one meter away at a right angle to the muzzle. The gun shoots more quietly with the slide locked by cable ties. The sound with the slide blocked and with unprotected ears is more reminiscent of a short, high whistling sound than a "bang." The whistling sound probably comes from the highly compressed gases exiting the suppressor with the bullet. The tinkering with the cable tie creates a single shot gun. A quicker way to reload is to place a catch between the slide and the grip, which is manually operated like a safety. An early example from the Vietnam War was the Smith & Wesson Model 39, which was supplied to the US Navy Seals as the MK 22 with a slide lock – but this pistol became a single-shot gun.
The suppressor always caused a shift in the point of impact. Depending on the tested load, between 1.96”/50 and 2.75”/70 millimeters. In our test, the shift was downward. With subsonic ammo, we were able to reduce the shot noise with silencer to the quietest value of 85 dB. This was achieved with the GECO FMJ TC (157 grs). On the other hand, the 113-gr Sellier & Bellot TC FMJ produced the loudest noise of 113 dB without a silencer.
Loudness: the first shot with the silencer
The "loud-first-shot" phenomenon is also present with the quieter subsonic cartridges. According to the manufacturer, this phenomenon should be able to be turned off by adding a few teaspoons of water into the silencer before firing. We generally refrained from doing this, merely tried it out with a load to see if and what happens – the firing noise is a few decibels quieter, it sounds "wet", but further handling of the damper should only take place after it has dripped out.
The actual volume of the shots depends on both the particular load and the barrel length. Every sport shooter is familiar with this fluid equilibrium: the soft cartridge fired from six-inch revolvers for 25-yard disciplines mutates into a rough cartridge with big muzzle-flash when fired from three-inch revolvers. Subsonic cartridges often have batches of special propellants designed to burn close to the muzzle. The silencer reduces only the bang of the high-pressure gases at the base of the bullet, not the concurrent supersonic bang of the projectile when it exceeds about 330 meters per second of the supersonic cartridges. As a rule, the larger the silencer, the better its attenuation performance.
Beretta M9A3 in 9 mm Luger specs and price
|Model: ||Beretta M9A3|
(L x W x H): ||221x35x143
Pull Weight: ||SA 2200 g approx., DA 4100 g approx.|
|Notes:||Second rubber wrap-around grip enclosing the grip frame, two spare magazines, ½"-28 UNEF muzzle thread and protective cap, gun lock, two threaded safety rings for silencer operation.|
Beretta M9A3 with A-Tec silencer: wrap-up
Subsonic cartridges vary in loudness, but overall are slightly quieter than normally configured 124-grainers, even without silencer. Very light, high velocity rounds like the Magtech 9d – the extremely harsh 95-grain bullet load – are again significantly louder than the mass of normal supersonic cartridges. These peak values were around 120 dB. The use of a silencer requires new zeroing and the installation of high sights. The greatest effect is seen with the slide locked, but reduces the gun to single-shot operation.