SBR’s and SBS’ too loud?

[MachIVshooter]

But I would disagree, based on my experience having to play tight "man coverage" as an RO to keep the timer working on some of these guys, that blowback 9mm PCC's are inherently louder.

Unsuppressed, certainly not. The muzzle noise will be higher than port noise on an unsuppressed carbine, say 155 muzzle and 140-ish port. But suppressed, you increase backpressure, so port noise tends to creep up a few dB, while muzzle end will likely be in the arena of 120-125 with subsonic loads and mid-130s with supersonic rounds. Conversely, locked breech 9mm pistols are gonna run in the high 150s/low 160s muzzle and but mid-high 120s with subsonic ammo through your average full size 9mm can, while shooter's ear numbers tend to still be sub-130.

Gas guns are a mixed bag, but most will have piston pop in excess of 140 dB, regardless of muzzle SPL. ARs with properly tuned gas systems & buffers can get shooter's ear numbers into the high 130s.

 

[Deputy25]

Back in the late 1980s I had occasion to fire a cylinder full of Federal .357 125 JHP from my service revolver during an event inside of a small house. I have dealt with tinnitus ever since. I'm used to it, but it's always there. My bedside pistol is suppressed.

 

[waterhouse]

I’ve shot a suppressed 8.5” 300 blackout with subsonics, a suppressed 12.5” 5.56 with regular ammo, and a suppressed 8” Sig MPX with subs all at in indoor shoothouse. The 5.56 was still loud, the other 2 weren’t bad at all.

 

[entropy]

The only experience I have with this topic is firing MP-5SD3's in a shoot house at the MOUT on post. While they are not as quiet as the movies make it seem, they were tolerable. I have not shot my 7" AR pistol without protection, and if I ever have to, hearing damage will not be the first thing on my mind.