Yes, supersonic is the goal for my thermal coyote setup. Having had the opportunity to shoot a 9" 300blk with subs I can see that it is drastically quieter, and it's not just the lack of the sonic crack. I believe 300blk is just a lower pressure lower powder round. Now that I have my SBR stamp I'm looking for an upper for it and 300 makes sense for some of what I do like coon calling and other shorter range hunting.
As for supersonic, I suspect that 300blk will be a touch quieter, but possibly not enough difference to mess with. Especially given that it's trajectory isn't quite as good as 223.
Shooting the 20" 223 suppressed does not seem very loud for 3-5 shots, but a couple hours later I start to get a dull headache. It doesn't bother a lot of people but my ears are just in bad shape unfortunately. Still MUCH better than unsuppressed.
