Suppressed and subsonic, they're fun. Other than that...meh!
I owned one, enjoyed playing with it, but bullets are expensive, it has the trajectory of a rainbow with subs, and it's another cartridge I have to load for.
I sold mine and put together a short barreled, suppressed 5.56. It's a lot louder than the 300, but odds are I can hit a target at 50, 100, etc. without having to hold way over, dial, etc.
The 300 is fun, but in my opinion, that's about where the usefulness ends.
