you can buy barrels, but i'd say most 300 aac short barrels are made for pistol-length guns so piston most likely not an option. raven or jard seem to be about it ...
300 BO without the ability to legally suppress in Canada makes this cartridge largely pointless in Canada in my opinion.
The whole point of it is to launch relatively heavy 30 cal bullets at subsonic velocities with a suppressor.
I guess there is a novelty factor with it, but even .308 can be downloaded with hand loads and retains the ability for hotter loads with it's superior case capacity.
I guess more choice is always a good thing.