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Posted: 5/8/2015 3:09:09 AM EDT
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I was watching some SilencerShop videos and was wondering about the Ear to Muzzle Db dynamic. see below (All tested on same host (AAC 16" MPW) and equipment)
Griffin Recce 5: Avg. Muzzle: 129.7 Db Avg. Ear: 144.1 Db SF SOCOM 556RC Avg. Muzzle: 137.7 Db Avg. Ear: 143.6 Db SiCo Omega (556 Cap) Avg. Muzzle: 131.7 Db Avg. Ear: 134.0 Db With the numbers above would the reason behind the Omega having the lowest number at the ear have to do with its greater volume? Does Ear Db basically have to to do with port noise? Why does the Recce do so well at the muzzle but louder at the ear? I wear earpro on full power 556 either way but just curious. Mind you of course the SF & Griffin are 556 cans and the Omega being a 30 cal can. eta: info |
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Port noise on a semi auto is significant and this is why the ear DB is higher. As to the difference between the cans ear db measurements I will guess this has to do with back pressure from the can. Silencers increase back pressure and cycle rate hence when the case is extracted you have a higher pressure released then without the can, more noise. Design of the can will influence the back pressure and overall volume in the blast chamber is a big factor.
If you install an adjustable gas block you should be able to reduce the port noise by delaying the bolt unlocking. Adding mass with a heavy buffer will also accomplish this. Why does the Recce do so well at the muzzle but louder at the ear? My guess, it is more efficient at keeping the gases in the can longer (smaller baffle bore size? greater turbulence? etc.) which is a key factor for reducing the sound level. Unfortunately this increases back pressure and hence port noise. |
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Quoted:
I was watching some SilencerShop videos and was wondering about the Ear to Muzzle Db dynamic. see below (All tested on same host (AAC 16" MPW) and equipment) Griffin Recce 5: Avg. Muzzle: 129.7 Db Avg. Ear: 144.1 Db SF SOCOM 556RC Avg. Muzzle: 137.7 Db Avg. Ear: 143.6 Db SiCo Omega (556 Cap) Avg. Muzzle: 131.7 Db Avg. Ear: 134.0 Db With the numbers above would the reason behind the Omega having the lowest number at the ear have to do with its greater volume? Does Ear Db basically have to to do with port noise? Why does the Recce do so well at the muzzle but louder at the ear? I wear earpro on full power 556 either way but just curious. Mind you of course the SF & Griffin are 556 cans and the Omega being a 30 cal can. eta: info 9.6 dB difference between SOCOM 556RC and Omega?  I know... still loud either way but 10 dB is probably noticeable.
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