On June 8, 2019 Discreet Ballistics decided to spend a perfect 75 degree New Hampshire Saturday taking a look at one of the more important of these factors. We measured the sound reduction of 36 silencers all shooting our 300BLK subsonic ammunition and 7 of these 36 were shot with supersonic 175gr 308WIN Federal Gold Medal Match. In addition to numerous representatives from silencer companies, we were lucky enough to be joined by a team from Brüel & Kjær as well as Erich Thalheimer a board certified acoustical engineer and former Brüel & Kjær employee. As some of you may know, the old standby for silencer testing is the venerable Brüel & Kjær 2209 which was last manufactured in the early 1970s. This analog instrument with its 20µs rise time is the current accepted standard for silencer sound reduction testing (Mil-1474D and Mil-1474E). Currently no hand held digital meter can come close to the accuracy achieved with the Brüel & Kjær 2209. We were fortunate enough to have Brüel & Kjær bring along some new hardware in the form of a semi field portable Pulse system which has gained the moniker “mini-Pulse”. So in the woods of New Hampshire we pitted two 40+ year old analog 2209s against a brand new digital mini-Pulse which had just received a fresh software update from engineers in Denmark to streamline its user interface.
To learn more about the new Brüel & Kjær mini-Pulse you can read about it here:
https://bksv.com/en/products/data-a...alyzer-system/Impulse-noise-evaluation-system
With us were representatives from a dozen silencer manufacturers some of whom made the trip from as far as Montana. Many of those who couldn’t make the trip graciously sent us 30cal silencers to test. We followed a relatively simple (albeit slightly modified) protocol. Standard 1474 distances were observed but due to some cable length limitations we opted to set up the 2209 and mini-Pulse microphones to the left of the muzzle rather than the right side. Two microphones were set up on the left side of the shooter 6” from the shooter’s ear. They were in direct line of sight with the muzzle of the suppressor. A Ruger American Ranch with a 16” barrel was used as a host and 5 shots were recorded per silencer. Additionally, a 308WIN Ruger Gunsite Scout with a 16” barrel was used to test supersonic ammunition.
Temperature and weight (with attachment device) of every silencer was recorded prior to shooting. Atmospheric conditions were recorded every two hours utilizing a Kestrel handheld weather station. A control silencer was shot to accompany the recording of atmospheric conditions to help account for any dB performance swings throughout the test day. A large LCD TV acted as a monitor for attendees to look at real time sound measurements.
We quickly began to notice a discrepancy in the readings between the 2209s and the mini-Pulse. Northeastern Sales Engineer for Brüel & Kjær, Steve Kawamura was manning the mini-Pulse throughout test day and he drafted a document to explain the deltas we saw between analog and digital systems.
It can be accessed here: https://www.scribd.com/document/413...ve-Noise?secret_password=lxbbXUH9lPFTofXwTnMT
In addition to collecting dB measurements we were able to collect shot “duration” data with the mini-Pulse. The following is from Brüel & Kjær regarding this measurement:
And finally the raw data:https://docs.google.com/spreadsheets/d/1NMuBVWhcK13kmjfQcP2otQhcJVyVzbvrZhgPOQFBe90/edit#gid=0
Our plan is to thoroughly analyze the results in the coming weeks and of course start thinking about our 2020 Silencer metering day where we hope to have even more great silencer companies attend!
To learn more about the new Brüel & Kjær mini-Pulse you can read about it here:
https://bksv.com/en/products/data-a...alyzer-system/Impulse-noise-evaluation-system
With us were representatives from a dozen silencer manufacturers some of whom made the trip from as far as Montana. Many of those who couldn’t make the trip graciously sent us 30cal silencers to test. We followed a relatively simple (albeit slightly modified) protocol. Standard 1474 distances were observed but due to some cable length limitations we opted to set up the 2209 and mini-Pulse microphones to the left of the muzzle rather than the right side. Two microphones were set up on the left side of the shooter 6” from the shooter’s ear. They were in direct line of sight with the muzzle of the suppressor. A Ruger American Ranch with a 16” barrel was used as a host and 5 shots were recorded per silencer. Additionally, a 308WIN Ruger Gunsite Scout with a 16” barrel was used to test supersonic ammunition.
Temperature and weight (with attachment device) of every silencer was recorded prior to shooting. Atmospheric conditions were recorded every two hours utilizing a Kestrel handheld weather station. A control silencer was shot to accompany the recording of atmospheric conditions to help account for any dB performance swings throughout the test day. A large LCD TV acted as a monitor for attendees to look at real time sound measurements.
We quickly began to notice a discrepancy in the readings between the 2209s and the mini-Pulse. Northeastern Sales Engineer for Brüel & Kjær, Steve Kawamura was manning the mini-Pulse throughout test day and he drafted a document to explain the deltas we saw between analog and digital systems.
It can be accessed here: https://www.scribd.com/document/413...ve-Noise?secret_password=lxbbXUH9lPFTofXwTnMT
In addition to collecting dB measurements we were able to collect shot “duration” data with the mini-Pulse. The following is from Brüel & Kjær regarding this measurement:
And finally the raw data:https://docs.google.com/spreadsheets/d/1NMuBVWhcK13kmjfQcP2otQhcJVyVzbvrZhgPOQFBe90/edit#gid=0
Our plan is to thoroughly analyze the results in the coming weeks and of course start thinking about our 2020 Silencer metering day where we hope to have even more great silencer companies attend!
