"And we buy guns because they are practical? Humpfff...maybe the first few."
Point taken. Were a BMG the same cost as a 22LR, I'd have
at least one BMG --I'd shoot the 22LR a whole lot more, for a ton of reasons, though
"I also understand how the decibel scale works, and that radiated acoustic energy in W/m^2 or sound pressure transients in Pascals are absolutely *not* synonymous with loudness, due to the physiology of human hearing. Perceived loudness is logarithmic, not linear (Fechner's law) and the decibel scale is a very good approximation of it."
Since all guns are well beyond the human hearing limit, well into the "pain" threshold area, I don't believe, based on my limited experience in damaging my own hearing, that the logarithmic scale defining volume holds at all. At these levels, we're beyond what our sensory can detect, and at that point all additional energy is going directly into 'breaking stuff,' and generally causing havoc. IIRC, hearing damage actually accumulates exponentially past the damage threshold, as I suspect do also the pain/disorientation. The reason that braked AR is so loud, is because you are getting the full experience of the muzzle blast, rather than being shielded from a portion of it by the barrel profile. Fire inside an enclosed room such as you'd find in a domicile, where your barrel is <10ft from any wall, and the difference in volume between braked/unbraked starts becoming moot.
I've shot a handgun indoors before and experienced just how loud they are, and I've fired rifles with plugs/muffs through gaps in close baffles --maybe not a whole order of magnitude difference between them, but perhaps three times as much concussion from the long gun, which roughly aligns with how much more powerful a 223 is than a 5.7x28 (you want a loud handgun, that's a loud handgun!)
"The biggest, most important reason is 'market opinion' in the shooting community. Not enough folks want one."
Seeing as how cheap, plentiful Korean M1 Carbine 30 rounders are around (can't for the life of me understand why, for the reasons espoused in this thread), and seeing as how Blackout is all uber popular, and seeing how people are crazy about pint-sized PDWs and subsonic silenced platforms, and are always looking for reduced recoil...
-AR15 pattern rifle with M1 Carbine mag adapter or magwell (ideally shortened)
-DI gas system, short carbine length
-223 brass cut down for 30cal bullets, loaded subsonic (I'm guessing 180gr or so, proportionally lighter than Blackout subs for the reduced case/powder volume)
-Large volume 30 cal silencer on SBR upper
-Overall lighter/smaller build, made practical by shorter mag & BCG travel length, as well as reduced recoil
Sounds like you'd have something that basically does Blackout's job, but with recoil more like that of a 22 caliber bullet. From what little I know of Blackout, you might even be able to match it ballistically for subsonics and not exceed allowable pressures (not much powder under those heavy pills, I understand)
TCB