Yes, and I think it's a great step in the right direction. Some days, when I get really optimistic, I even think it might help bring mechanicals (Automags!) back to common use.
I've got a loudener on my AT-10. Don't know who made it, though. It's about as loud as a Black Cat (firework) each time it fires. It makes me happy.
I doubt that Kingman's pistol will do anything. It's not much different from cRAP4's .43 pistols, and there still aren't any major companies producing .43 paint, nor are there any non-niche guns-they're all mag-feds or pistols.