Some Useful Tests On Suppressors
BY Herschel Smith
5 years, 4 months ago
Via David Hardy, some useful tests on suppressors.
For our testing purposes, we used a *Larson Davis Model LxT1-QPR Sound Level Meter.
We recorded both suppressed and non-suppressed readings, using the z-weighting method of measuring high pressure levels. This method of measurement is also referred to as linear or unweighted.
Unweighted is a more accurate method of evaluating potential hearing damage and is the best method to use when testing firearms. MIL-STD 1474D is considered the military standard for measuring sound. Following these standards, we placed the microphone 1 meter to the left of the muzzle and 1.6 meters above the ground, with the microphone pointing upward, at a 90 degree angle to the bore. All testing was completed away from any reflecting surfaces, as to not negatively affect the audio readings.
We compared five of the most popular handgun and rifle calibers available on the market today, testing 30 different SKUs of ammunition in the process. Then, we test fired five rounds suppressed and three unsuppressed with each brand of ammo to find an average dB level.
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Unsuppressed, we recorded an average of 166-171 dB for the 16″ and 20″ AR15 rifles. When shooting with a silencer, the levels come in at an average of 135-145dB. That’s an average reduction of 36dB between the unsuppressed and suppressed shots.
We observed a change of only 1-4dB between the two barrel lengths, both suppressed and unsuppressed.
Of all the rifle calibers tested, the loudest average unsuppressed measurement of 172.87 dB came from the 18” Ruger American Predator, firing .308 Win Federal Gold Medal Berger 185gr. OTM ammo. The same ammunition fired with a suppressor came in at an average of 148.4 dB.
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We saw comparable results for 45 ACP as we did with 9mm. The average unsuppressed levels, which were some of the loudest results for the pistol calibers, came in at average of 165-167 dB, while the average suppressed levels came in 21-26 dB lower, ranging from 141-146 dB.
This is useful, but I do have one gripe with the data and the explanation. An unweighted measurement of sound is not the best or most useful for evaluating hearing damage, regardless of what their cited Mil Std does or doesn’t say.
OSHA uses A-weighting because that is the weighting that most closely approximates the effect of frequency differences on the ear. So does NIOSH, and ACGIH. That’s what the military should be doing.
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