This is a little bit LARPy, but what the heck, we do some of that from time to time around here.
I've been contemplating a defensive-use, AR-based rifle built to "Utopia spec," i.e., no evil features, for awhile. The idea would be something that can be quickly and easily taken down to travel relatively incognito in standard-size hard-sided suitcase-like luggage, and reassembled when it's time to have a long gun available. A 1301 could be an option, but once it's all set up with lights and mag extensions, etc., it's really fiddly to take it apart and put it back together. The AR paradigm of punching a couple pins is much more attractive than fiddling with mag tube springs. Utopia is a no-fly zone for the NFA, so it will have a 16-inch barrel, no flash hider or can. A blast deflector that is not a flash hider in Utopia would be in bounds.
All the talk in the PDW thread has gotten me thinking about possibly using .300 BLK instead of 5.56. The idea behind this question is just the potential reduction in hearing damage in the event that it had to be fired without ear pro, possibly indoors. Obviously, supersonic .300 BLK is not going to be hearing safe, so it's like deciding whom to vote for in a Presidential election: Which one will do less damage, more slowly than the other? Is the difference enough to matter?
Burning ~25 percent less of a faster-burning powder for more time and expanding it into ~90 percent greater volume while doing more mechanical work (taking energy out) before uncorking it seems like it should add up to something significant, at least measurable if it's measured the right way. But does it make a difference in practice?
For subsonic rounds at personal defense ranges, I figure one might as well just go with a 9mm PCC and load it up with 147gr HST or Gold Dots for all the reasons that don't need to be itemized here. Which is probably worth doing a comprehensive pros/cons analysis anyway, but for now, let's just stipulate that the superior on-target effect of .300 BLK is great enough to stay focused and stick to the original question. (It approaches the ~2300 fps threshold to do rifle stuff instead of just poking holes in things.) Also, the only current-production, OTS PCC I'm aware of that doesn't have the same evil feature problem as an AR is the Ruger, and its barrel keeps falling off. I've told Ruger in writing that I'll buy one as soon as they make it with a non-fall-offable barrel.
I've spent quite a bit of time googling and can't find much on back-to-back comparisons between unsupressed, 16-in barrel 5.56 vs .300 BLK supersonic sound levels. Anyone have data or know where to find it? Anyone have subjective impressions from their own experience?